You've taken a great step by simply asking. Keep researching! and also start with simple things. Like simple 5 minute breathing exercises and meditating. Go to bed early and rise early. Make a healthy meal plan and exercise regularly. Baby steps. A baby step is still better than no steps at all. Don't be too hard on yourself. The pressure and stress you're giving to yourself is probably stifling your productivity also.

With that said, also don't be afraid to fail. A lot of the time when you experience failure, it just means you need a bit more time and experience until you do succeed. It could also mean that you need a change of direction. You are still really young right now and sometimes it takes months, years or even a decade or more to figure out what you really want.

I've changed my major over 3 times. It took me almost 10 years to figure out what I really wanted and I'm now working at my dream job. I failed many classes when I first entered college, it was only after I experienced many failures that I began to mature and learn ways to really succeed.

Go get some motivation wherever you get it from but once you have enough motivation ammo, spring forth to action as soon as you can and really keep it going as long as you can. Once you run out of steam, look for more ways to be motivated. Getting a pep talk or reading an article is great. Having mentor that is in your field is also a good idea. Writing down your goals would be a great first step to declutter your mind and refocus on whats really important.