Ways to increase focus
 

So these days I'm having a really hard time concentrating on my course work. It's not that I don't like it so i'm procrastinating.. it's I just can't sit still and focus for 3-4hrs.
There is an evaluation at the end of this thing which is 4hrs- i'm feeling nervous.

Any tips to increase focus naturally? Like better diet or something? Not looking for pharma options.

I would suggest you try mindfulness meditation.

A brief daily meditation is very effective.

There are guides on youtube; the less new agey ones tend to be best.

Here's an article on the subject.
Annie Murphy Paul: Can Mindfulness Technique Help Us Focus? | TIME.com

Six Scientifically Supported Ways to Crush Procrastination

Exercise also helps with focus. I find that a 30 min run before studying/exams help a lot.

Well rested sleep also helps.

Confidence by throughly practicing what you're being evaluating on really helps to. Not only will you be prepared, you'll be a lot calmer too when the time comes.

I know you don't like pharmaceuticals but they do help. Adderrall, wellbutrin, caffeine, ephedrine, all help, as they are stimulants. But use them sparingly and don't take them all at once, or they have the opposite effect. The jitters suck.

earplugs, library, cell phone OFF.

done.