It is hard because so many people cannot be brought to realise that when B is better than C, A may even be better than B.
C.S.Lewis - Mere Christianity
This book is amazing to me. I highly recommend to take some time, get a copy and just read this book. It is things every one of us could have thought - to some extend perhaps should have thought. Yet most of us haven't thought that way. C.S.Lewis was a great mind and whoever wants something to read besides his bible, might as well start with him.
The interesting thing about this quote is, how often indeed we cling to a pleasure and try to get back the thrill, we felt at first, when it is meant to bring us to other new pleasures when worked out in a right way. You will lose the thrill of a beautiful spot some time after you moved there, but you might experience a new pleasure there, like gardening, drawing closer with the people, fishing or whatever there is.
In what areas in your life might you have gone wrong in clinging to B, when there was an A to move on to?