I think the more time you spend outside the better. For me it is that way. If you live in the city it takes even more time to go to a place that one can call "nature". I am very happy because soon I will movee to a flat with a forest only 10 mins with the bike. Finally :) But there is nothing better (for my wellbeing) than spending some days outside hiking with a tent to sleep in and clean rivers to swim.