Best ways to fight fatigue when coding?

If you feel like taking a break, just take a break. :)

When you feel better, come back to it--you aren't any worse for doing so!

Back when I used to work a second job in the evenings, I used to get home around 4-5pm in the afternoon and have a nap. No more than 20 mins (set the alarm clock!). Made a huge difference.

Try coding on a hammock.

Hammock Driven Development https://www.youtube.com/watch?v=f84n5oFoZBc

First, don't set deadlines that make things difficult. Give yourself time to do the job properly. If the client is too demanding, they're going to be a problem in other aspects of the job as well. Gaining respect first comes from respecting yourself.

Second, get plenty of quality sleep, that means no caffeine/alcohol for 6-8 hours before bed, and allowing yourself at least 8 hours of uninterrupted sleep.

Third, when working, get up and walk around once an hour, for at least five minutes. Have a healthy snack, do some push-ups, walk around the block, anything but sit.

Fourth, exercise! Do something that makes you sweat for at least 30 minutes a day. This one is a must, no excuses.

Fifth, stretch. This can be done during your five minute breaks. If you do nothing else in this list, do wrist flexor and extensor stretches (look them up). Otherwise, your coding career can get cut short (speaking from personal experience). Stretching takes 2-3 minutes and can make a world of difference; do them every time you're feeling stale. It's not possible to stretch too often.

Next, eat right. Keep your diet light, skip the soda and chips; eat fruits, nuts and veggies, drink water. You're already sitting on your ass all day, don't make it worse by fueling yourself with garbage.

Finally, have some hobbies that don't require a screen. Go hiking or biking. Play a sport. Learn an instrument. Bird watch. Build a tree-house. Catalog all of the different bugs in your yard. Whatever, just get away from screens.

All of this is obvious and a no-brainer, right? Well, look at the people who have been in a field for 20-30 years, the ones who stick to the above are easy to spot; they're the fit, happy, healthy people. The others are easy to spot too, because they look like hell. Get into these habits before you need to, you'll be saving your future-self a lot of trouble.

Hope that helps. Time for my workout...

Block 9gag with /etc/hosts or https://getcoldturkey.com/ or https://selfcontrolapp.com/ and spend the entire time on sleep.

If you aren't getting enough sleep, that is the reason you're fatigued. Prioritize fixing your sleep over everything else because without a well-rested brain, it is impossible to consistently write good software. Without writing good software, you can't hit your deadlines.

Seriously, your brain is a part of your body. Take care of both of them. This isn't just some feel-good advice. Taking care of yourself is actually necessary for solving difficult problems.

Also, make sure you understand the abstractions you are working with. Not doing so means you go around in circles. Make sure you have a clear "Definition of Done" for what you are building. Not doing so means you're going to go back-and-forth with your client/employer/TA and waste a lot of effort. Make sure you write automated tests as you write your code. Not doing so means that when you write a bug you could spend hours trying to chase it down.

Don't treat necessities as if they were luxuries.