1. Meditation, but I don't think it would have landed earlier.

2. Insights from 1, like it not being my job to solve problems, it's my job to show up and orient myself toward the problem. Whether it gets solved or not isn't really in my control.

3. Relaxation is a skill. Like most skills, especially ones you've never trained, a small amount of deliberate practice yields large improvements.

4. Note taking system I enjoy using.

5. Increasing typing speed and buying the keyboard that maximizes speed after testing.

6. Desk ergonomics

7. Getting rid of most belongings a la Marie Kondo

8. Food allergy testing

9. Doing things that take less than five minutes immediately a la Getting Things Done

10. Training to notice hamster pellet loops aka news feeds, notifications, etc.

11. Creativity training a la The Butterfly and the Net

Currently undergoing a CBT program for improved sleeping. It is literally giving me 3-4 extra productive hours a day. (By cutting down roughly 1.5h of lying in bed not sleeping, and sleeping overall 1.5h-2.5 less.) That's roughly an extra two months every year.

It's the most surprising and effective productivity thing I've done in years, and costs only $25 a week + 1h of watching instruction videos, and some energy/mental effort of sticking to the routine.

Though note that I've only done it for 2.5 weeks and expect the final improvements to land on 0-2 extra hours per day.

Exercising semi-regularly, and eating semi-healthily. I wish I could send a specific advice to my former self, two decades ago. The "specific" part is important, because I have received lot of advice which was either wrong, or just strongly incompatible with my preferences.

Without going into too much detail, the specific advice optimized for me would contain:

• Instead of doing sport, do strength training at home, and take walks outside with friends or optionally alone when no one wants to join you. (You get the benefits of burned calories and fresh air. You don't have to rely on any person, or opening hours of a gym.)
• Eat fresh vegetables with every meal. Buy an extra salad when eating outside.
• When possible, cook for yourself. Try a few recipes, keep the simple ones that taste good. Use less sugar and salt; compensate with spice. (Almost anything cooked at home is healthier and cheaper than what you would buy otherwise. The more you cook, the better you get at it.) If you eat outside, Asian food usually contains a lot of vegetables and tastes great.
• You don't have to find out the "one true theory" of nutrition and exercise. Just accept that most of what you hear is pseudoscience, and focus on the few things that most people agree upon.
• Be a satisficer, not a maximizer; aim for sustainable progress, not purity. If you do most things right most of the time, it doesn't matter if you break the rules once in a while. (If you make a vegetable salad for lunch, don't worry about the extra calories in dressing. Instead, worry about forgetting to make the vegetable salad also the next day, and the next day.)

Being pro-actively social, learning social interaction and dynamics.

Sleeping full nights every day.

Saying no to unhealthy social pressures (ex: smoking weed to fit-in)

Making lists and writing every day.

Journaling. Writing down exactly why I am taking the important decisions in my life, and then later on looking back on that journal and evaluating/correcting my decision making process.

Also wish I had more control over my environment earlier on. Ex: I lived with a cat for 4 years despite being allergic because everyone in my family wanted one. Looking back I think this caused the sinus problems I now deal with. Also my family had terrible nutrition when I was growing up, which I believe impaired my body's height and ability to gain muscle.

I think the main one for me is learning to be productive