It's a mistake to approach brain physiology and mental heath separately. These two concepts are totally interconnected. Today, we know that brain doesn't have a solid structure. It constantly reorganize itself by creating new connections between brain cells. This characteristic of brain is called brain plasticity. So every change in our mental condition is actually caused by the physiology chances in our brain.
It can be tricky to detect cause-effect relationships when it comes to mental health. Because literally every input that we get from our senses has some kind of effects. Simplest things in our daily life, such as listening music, drinking coffee, talking to someone causes many different internal mobility in our brains. So it's hard to give an exact blueprint, however there are many proven ways to improve mental health. I will talk briefly about three main factors.
Exercising
There is a wide spectrum of academic studies about the effects of exercise on our mental health. Studies show that exercising increases endorphins and dopamine in our system. Actually exercise if so powerful at increasing those mood booster hormones, it's addictive. Also there are some indirect effects such as increase in self-confidence by getting in a better shape. I will write much more detailed posts under the topic of fitness in the future.
Eating Good
Foods have a much bigger effect on our mental health than you think. Modified sugar (such as glucose-fructose syrup) and chinese salt which are used by nearly every fast-food chain have effects our brain just like drugs do. They are highly addictive. They cause a lot of dopamine release, as a result you brain becomes more and more senseless to dopamine in time. Eventually you don't want to eat anything but those highly addictive foods which have almost no nutritional value. In addition to that, high amount of sugar causes insulin resistance and it gets harder and harder to feel satisfied by eating just enough. Your body starts wanting food because of deprivation, not the real hunger. This deprivation is also called toxic hunger, which has nothing to do with your bodies need of calories and nutrients. Again, I will write much more detailed posts about dieting in my future posts. Will talk about what we should eat, when we should eat to increase our life quality but i have to cut the food part short just for now. As always, I also encourage you to do your own research and thinking on these important subjects that affect our life directly.
Meditation
Before talking about meditation, I highly recommend you to read a previous post of mine about anticipation. I talked about how our brain get affected by the stimulation. We get exposed a very huge amount of stimulation by our environment. This is too much to handle for our ancient weapons called mind. Mind starts to get resistant to stimulation and we even loose our ability to be alone, just by ourselves without a computer or a smartphone eventually. So basically meditation works as a re-calibrator for our minds. It is very beneficial for long-term also. We teach our minds to find piece in silence again. But it is a process. There are many different meditation forms. Most popular one is called transcendental meditation. I also recommend you to make your own research of meditation. I don't know if I will write a detailed post about meditation.