You keep going. Every project you give up on you keep trying again on something new.
I always suggest having three things to focus on, three projects, that could be for fun, hobby, family, or side project related. Something that allows you to take your mind off one thing, and focus on another.
Hell, you could create a project that has three very different components that all come together eventually.
If you still can't keep the persistence, than that's fine. You have a stamina gauge for any activity, you need to do what any marathon runner would do — keep at it. In any project you will eventually run out of steam and your interest will wane,you have to give up on some projects and just go a little bit harder in the next project. Build up your fortitude and try to make every new project last a little bit longer than your last project.
1 to 2 to 3 to 6 to 12 to 24 days, weeks, months. Eventually you'll build up your resilience and your confidence to accomplish great things.
If you're a gamer, this is your experience tree. You need to max out more skills in more areas, level up, and keep going till you vanquish the beast at the end of dungeon with a two hit swing and not a thousand health potions and reloading a save a million times.
You'll still fail in a lot of things, but you'll learn how to accomplish more things and keep the persistence to keep going when you are stumped.
Those are some my thoughts on the manner, I hope they help.
Side note: I don't like self-help, and must say that you shouldn't read any of those books or watch any of those videos as they are just trying to get you to spend money on their merchandise and will send you down a depressed hole. They make their money empowering others, not accomplishing real tangible things.