But one thing I do: Forgetting what is behind and straining toward what is ahead, I press on

A runner strains toward that goal -- that prize!  It takes focus, energy, exertion!  He could be running next to a beautiful river, but he only focuses on what is right in front of him.  

Personally, I'd rather my faith look more like a fun dance than a strenuous run, but sometimes we get one, and then sometimes we get the other.  But let's keep at it!  Regardless of what else may be going on, the supreme joy of life in step with Jesus Christ is not to be missed.