Rule #1 in Peterson’s Rules For Life book appears to be all about physiology and might appear as ridiculous on the surface - but it is so wise. I liked the coverage in these two pieces on the internet:
Part 1: Stand up straight with your shoulders back
We don't have to wait for something to make us feel happy or "good". We can totally create it any time we want. Do these and then add doing those things that are meaningful and you'll be able to go through the portal to the greatest life. (See, when you have time, Maximizing Meaning In Life.)
THE STORY OF OUR HAPPY AND OUR UNHAPPY CHEMICALS - A TALE OF THE MECHANISMS FOR SURVIVAL.
From there you could both go to the pieces on learning how to get your own good feeling chemicals, from within< AND the ultimate of all feeling that lies in experiencing something of great meaning (and how that connects to the survival mechanisms).]