I like jogging in the park. It makes me forget about problems and "refresh" my brain after work.

I can say only what I do to relax after work ;)

best way to meet friends, if possible

If not I try to go out myself or I do what I like best. I compose music or play guitar.

Or I do sport... As a variant I can go to the cinema.

The point is to forget about studying or work and do completely different things.