He did a better job of addressing this issue than Noah Kagan, who was talking about mild fatigue rather than real depression (yes, there's a huge difference). Let me add:

6. Exercise, with a mix of activities: swimming, running (outdoor is better) and strength training. He mentioned that the brain interprets social isolation as a sign of low status. It also interprets physical activity (or the lack thereof) much in the same way. Using your body (running, swimming, hiking) tells the brain that you're an alpha and that it needs to step it up a notch. Mild depression is when the body and brain go into gamma mode (more severe depression is a biological dysfunction of that system) which would be a form of hibernation, as observed in medieval mountain communities during winter, but society isn't tolerant of that, so it leads to misery. (Some mild depressives would be fine, aside from the loss of time, if they could sleep 11-14 hours per day.)

7. Avoid cigarettes at all costs. Use alcohol sparingly: one drink is fine, but it takes a week to recover from a night of serious drinking... and if you're coding, you actually notice the loss. Avoid drugs like cocaine and heroin like the plague. Jury's still out on occasional use of LSD or shrooms (but people with any history of mental illness need to be very cautious) but they certainly shouldn't be a habit.

8. Relax. Sometimes it's necessary to spend time in the woods and just (sorry for sounding hippy-dippy) be mindful. 24/7 Internet connectivity is not always helpful.

9. Read novels and watch movies. There's something healing about narrative that isn't provided by (as much as they are enjoyable to read) books about formal semantics of programming languages.

10. Music. It helps. I have a lot of friends who say they never would have gotten through their teenage years, or a bad turn of business, without music.

11. Go somewhere new, do something different. It doesn't have to be an "exotic" or expensive vacation; if your goal is to heal, it's better that it not be. Just a trip to visit friends 50 km away can help.

12. 2 weeks of real vacation, as an absolute minimum, per year. Take unpaid leave if you need to. Four weeks is best. Total productivity is maximal at 3 weeks of vacation and per-day productivity is maximized at 7-9. Europeans have it figured out: you need two types of vacation: exploration vacations to new places (Alaska, Cambodia, Andes) where difficulty and stress are OK and relaxation vacations where stress levels are low and variation of activity is not required. Unfortunately, Americans get stuck having to choose one or the other, and generally do only the first kind of vacation when they're young and only the second kind when they're old.

For the record, if you only get 1-2 weeks but can take unpaid leave without it hurting your career, you probably should. A 2% pay drop for an extra week of vacation is worth it IMO.

13. Fruits and vegetables. The casual arrow is unclear and probably goes both ways, but depressed people tend to eat a lot of white carbs. Americans tend to get dieting wrong, as if it's some set of religious prohibitions that have to be followed to the letter, when in reality there are few foods one should never eat. Instead of dieting negatively ("I won't eat X") it's better to diet positively and replace unhealthy foods with better alternatives (e.g. 70+ percent of your desserts should be fruit).

14. "Don't fuck crazy". High-power programming/technology, as a career, is only 10-20% more time-intensive than the average job-- you haven't seen bad hours till you've worked on Wall Street-- but it's 200% more energy-intensive. You need a supportive and decent partner who will be your rock of stability, not someone who will drain you.