Like so many of us, Phil is pressed for time. An avid mountaineer, when he prepares for a climb he wants to train just enough that he can summit and descend in a safe amount of time. He has a strategy (certain amounts of running and stair-climbing) to achieve that fitness level.
Last year a back injury precluded his usual training approach. The injury didn’t mean he couldn’t prepare to perform at the required level. However, it did force him to look for alternative strategies to train.