What is preventing me from improving my life?

Well I think the problem is you think too much. Com'on, if you keep on reading personality development books and think about how to improve, Where do you get time to improve? Just stop thinking and start working. LIFE IS THE BIGGEST BOOK it will tell you everything, all you need to do is listening

Think Again
You should just focus and think again what would be the benefits of your corresponding actions. Improving and changing once life was really hard, but if you will just continue being with it then somehow you will be fulfilled and find the things you deserved. For instance, If you're just being stuck into something do you think can you still achieve your dreams? So do something and remember why you're doing these. And consider that these improvement can't be done immediately, there is process on it just do it gradually until you've noticed you're fully a better person.

Slower is faster
try to apply what you want to change in your life. change will be come hard if you only think about this without including acts.

You get out what you put into the world. Even if things are shitty try to take a positive stance on them. If you keep going into the same cycle try different things everyday, they don't have to be huge differences from what you do now, but just try something else. I know for me it was the people i use to hang out with, so I got rid of toxic people and I feel a lot better about myself and my life/choices. I hope you feel better soon!!!

Think about the specific ways you want to change. Do you want to move? Do you want to go sky diving? Keep a goal in mind--just one, and start by pursuing that single mindedly. Take the first step on Monday the second on Tuesday. Not feeling up to it on Wednesday? That's okay, take a break, but you have to make yourself continue on Thursday. By the end, you may hate the thing you set out to do but you'll have done it and completed it. That's a step. Then form a new goal and repeat.

You can't just decide today you're going to be happy! You can't say today I'm going to stop being depressed! Depression doesn't work this way. If you're feeling a bit blue, maybe it's because something happened in your life. Example: A break up, a death in the family, a fight with a friend. But if you wake up every day feeling BAD for NO APPARENT reason, then this is depression. Of course when it lasts long you could be depressed because of an event in your life. But happiness doesn't come this way. In fact, I believe happiness comes and goes, it's not a permanent thing. As for being lazy, that you have to fix yourself. Just get up and DO IT. Take the first step. Once you get into it, you will finish it. Reading tons of books is insightful but it won't help you. The only person who can do it is you, and no author, video, or blog is going to do that for you. Also, being negative about it doesn't help at all. Instead of going on about how you can't change things, think about how good it would feel to overcome this change! Think about the things you want to achieve, how you would achieve it, and how fulfilled you will feel after you do. Remember your thoughts attract. Keep thinking how you're not changing, and you really never will.