There is only one path to happiness. You must identity your purpose and do everything in your power to actualize it. If you do that, the rest will follow. First of all, merely having a purpose, your mental condition will be normalized and optimized. And you will then take care of your physical health, since, in order to pursue your objective, you will need your physical health and will therefore do everything you can to hold keep it. If you don’t have a purpose, you are simply drifting, in which case, if you are happy, it will really only be by chance.