I've been asked multiple times - How long are you going to do this? And my answer is always the same. As long as it remains fun. And I believe this should apply to everyone - whether you are a pro or a beginner. Life is way too short and full of way too many options to do something you do not absolutely love.
And while training may not always be easy, I still believe the majority of time spent in your chosen sport should be fun. If you seem to have misplaced it, I challenge you to go find that love of sport again. And if you are having trouble locating it, consider branching out and trying something new.