Started reading the TAOCP from Knuth, but I’m depressed since it’s hard

In the coming years I started to lose my computer skills. Decided to refresh them by reading the art of computer programming by Mr. Knuth but some exercises are too complex that that I’m losing the motivation.

What can I do to improve myself? Basically I would like to re-learned most of computer fundamentals, since I noticed that I know how to program something, but most of the times without really knowing how the things work.

Also learning isolated and by my own is not that great.