There are no such things as “relaxing” or “to relax”. There is only “being relaxed”, the mental state.
By saying that one can relax himself, we tend to precieve that relaxing is a verb, an action. And right there, the contradiction starts. If it is an action, how can it bring relaxation to one? So humans tend to try out different things which they call relaxing. But they are just what they are: partying, sleeping etc. When they are over, we are stressed again.
Humans need to adopt a certain way of doing things to actually stay relaxed. That way of life needs to cover all aspects of his life, not bound to a certain time. But before that, they need to figure out what that way is.