Eat healthy. Do sports. Sleep well. Repeat.
Also, meditate, fast intermittently, get therapy, and develop healthy ways of handling stress and dissatisfaction. Everyone’s path is a little different. What is only a little difficult for some might be downright impossible for others (or feel that way).
General advice that would work for 95% of people shouldn't be criticised because it doesn't address the other 5%. If people did it then there'd be far more money in the system to pay for usefully targetted specialist treatment for those people.