It might be better to think about what happens if you don't do it. If you feel compelled to do something but don't do it, does it stop you from doing anything else? Does it override your thoughts? Or can you get on with life as usual?x
An example of an impulse would be a desire to eat ice-cream. A desire to mow the lawn is a rational feeling. Note that both of these have value of their own, I.e. they are good for you on some level. However, in my experience, a compulsion is an absolute waste of time.