DC - I'm often posed with this dilemma. So I relate it to what we're doing in PT and my long term goals.

By the end of the month I WILL be able to do 20 push ups

By the end of the month I WILL be able to increase my weights to xyz doing abc exercise

I WILL be able to do the prone position for xyz time

I WILL be able to do 25 min on the cross trainer

and so forth