If you manage to keep it every day, your project will advance fairly quick. One of the key thing is that when you hit a snag, you won't see it until the next day when you may have a completely different way of thinking about it. So all in all, it's a lot easier than working 4 hours in a row.
Also, don't commit to it daily, but commit to it more days than not. When I was really keeping up the gym habit, I had 2 1/2 social nights a week (Monday, Wednesday, sometimes Friday). I'd usually have time to bring a book to read or a notebook to write in between the gym and the social obligations. It helped that I lived near my gym in a downtown area near where I usually met people, I had a ton of time freed up not commuting.
Make it 2 minutes every day, consistently. It's short enough that you won't have an excuse not to. Don't waste it on planning; it has to be something that actually moves the project along, but you can plan later.
I used to be exhausted after work too, especially with a 3 hour back and forth commute. The side project should energize you, not fill you with dread. There are times when you physically need rest, and you should.
1. Yes, it's only the mornings that have worked. After a full days of work the mind can't quite switch context back to the side-project, so getting this done first thing in the morning is best.
2. Take a detailed note before switching context out about what were you thinking and the next steps. Read that back to get a jump start. Repeat.
3. Sleep early. Completely ditch alcohol. Cancel Netflix etc subscriptions. Limit coffee. Sound, restful sleep in dark and quiet (earplugs if you have to) is essential for pulling 10-11 total productive hours a day.
4. Exercise. Outdoors, in fresh air. Even a bit of cycling will do. Fitness and stamina go a long way in building focus and working those extra hours. I cycle to work (well, before Covid and after) to accomplish this specifically to keep fitness levels sound.
5. Turn off distractions. Phones off/flight mode with screen facing down. Told friends and family that they shouldn't tempt or distract. Even had to let one-two friends go because I realised I was always fixing problems for them and they had come to expect them to be fixed in x hours. Email/chat apps off. Anything that can prompt a notification is off. Issues can always wait a couple of hours.
6. Solitude. Or noise cancelling headphones just turned on.
As someone who works a full time job that I love but drains me, I need to be really motivated about something and curious about it to work outside hours!
Right now for me it is Java+Spring and Golang, I did some contributions to big OSS projects (mind you, the contributions were very minor. Like typo in docstrings). And am also doing a small side project (mind you, I got the springboot crud tutorial to run with my POJOs and bought a domain!)
If for some reason it becomes an energy drag I will drop it. I have already dropped more than 20 domains of side projects and that's OK. I will playing video games for a while or watching netflix.
If I am not getting paid to do it then I really have to enjoy it! I usually scratch an itch for a while and then give up, maybe when it happens that I don't give up in one idea of side project is because I truly enjoy it and it can become a full time thing to me!
My advice is if you or your family need more money then do a side project. If not I've two suggestions;
Have a hobby instead of a side project and take the pressure off.
Invest more time in your friends and family.
I have had side projects for 20 years. Born out of necessity, then supported by my employer, now the backbone of my startup, https://whoohaz.com
Just don't do that. That might sound flippant but it really is the answer. The most productive people I know simply do not lose weekends to hazes and Netflix binges.
Waking up early seems to be one of the main traits of those who end up making side projects or some good amounts of money.
The only problem is learning how to wake up early. Every time I wake up early it's like I forget the reason why I did it.
First of all, I think the standard advice of get enough sleep, eat healthy, exercise and stay within a reasonable weight (15%-20% body fat - lower if you can manage it) will solve the physical aspect of the energy equation. If any of those are off balance for you, get those sorted out. It will help you immensely in all areas of your life.
I also will assume you have strong motivation for working on your side-project. If it's to hopefully launch your product, learn a new skillset or whatever, if the idea of working on it doesn't itch in your brain all the time then sort that out. I think if you don't have a strong internal motivation for working on your side project there is no way that you're going to spend one hour a night, let alone four to five.
I'll go with the idea that you're trying to build a software product (let's say some kind of SaaS). Come to peace that building the product cannot and will not have the momentum of a rabbit but will be the lowly turtle or the snail. Accept this and be ok with it.
I think the biggest factor of success when working on the side on something is planning beforehand. I believe to build motivation for working on the product in your free time you have to know that you are making progress and there is light at the end of the tunnel. Planning is a critical aspect of this. To achieve this, you have to put on your product manager/architect hat and really figure out what the feature set you are building needs to be for the MVP, how much of what you are doing is going to involve learning new tech and/or how much you can do with what you know.
If you can validate your idea beforehand in some concrete way it will automatically be a motivation booster. If you cannot, focus on the most basic MVP that you can go to market with and accept that it may go bust. From this a good set of development tasks can start to be developed. Put an estimate on each of these and try to come up with a rough enough of hours. Let's say it's a 1000 hours of effort. Now, you can break that down into a date based on how much you can commit.
In terms of how much you can commit, I think we all know ourselves best. I certainly can't work 4-5 hours on my side project on top of a full day of normal work. I also certainly don't view those people with any kind of admiration. I need time with family, to exercise, get enough sleep, hang out with close friends, to chill, etc. and those take time. For me, I can't neglect those things. Be true to yourself and look at your schedule. Be critical about it. Realistically, how much can you commit using the week as a guideline and not daily. Can you do 4-5 hours a week? Great, do that. Start with that. There is good possibility that you will increase your weekly hours once you see progress.
Assuming the 1000 hours and 4-5 hours a week, now you kind of have a target date that you can measure your progress. Take your high level development roadmap and start breaking it down to a point where you can start actual work. Break it down into steps. These can be coding, reading, design work, researching, whatever that involves the side-project.
Personally, for me, I use a simple markdown file, open in Vim with the following:
# Next Steps [ ] Item one [ ] Item two
# Completed
Date [x] Item three [x] Item four
Date [x] Item five [x] Item six
# Review as Needed [ ] Task or design decision that is important but not relevant right now
# Defer [ ] Task that was part of next step but for whatever reason is deferred. Reason is provided.
When I am working, I will move items to the the Completed and add new items in the Next Steps near the end of the work session. I found this is the simplest and completely ceremony free. I tried Trello and other sprint planning type tools and I'm not that type. At the end of the day, you need to start working on your side project. If Trello or some other planning tool works for you then use it. For me, I realized I was wasting more time with the tool versus doing real work. The simple file gives a great overview of how much I've already done and when I start working again, I just look at the first line in the Next Steps and get going.
I think personally what has been the most effective for me is to just start working on it with a plan in place. I know that it's going to be months before I reach my development goals but I'm ok with this. As long as I can say, that I made progress during the week however incremental, it was a good week.