We need hobbies to relax us when in sorrow, or in depression. We need hobbies to synthesise ourselves, or to revive ourselves.
We need any hobby to keep us active throughout the present day, i.e., in a whole, we need hobbies to keep us active throughout our lives.
We need hobbies to maintain ourselves; and, to lead a peaceful, and prosperous life.
Hope this will help you. :)