Gardening is not trivial. If you believe that it is closely examine why you feel that way. You may discover that this attitude has been forced upon you by mass media and the crass culture it creates and maintains. The fact is gardening is just the opposite - it is or should be a central basic expression of human life.
I think theatre is by far the most rewarding experience for an actor. You get 4 weeks to rehearse your character and then at 7:30 pm you start acting and nobody stops you acting with your entire soul.