As I set down to plan my day this morning this quote was the last thing I read after setting out my targets for the day and what I was grateful for this morning.
The way in interpreted it was to stay focused on your goals. Make sure you are clear with what you want to accomplish and allow that clarity to move you forward. Should you get off trac you will feel the stress from losing focus or feel the pleasure of staying focused.
This is could be applied to many aspects in life, but for fitness get clear with your goals to allow you to stay focus on reaching them.