Have you ever noticed that you walk left foot first, you know "Hup Two Three Four"? Or walk to the rhythm of a tune ringing in your head, left foot on the one beat? Or even start walking the stairs with your left, always?
Here's the challenge: Hup on the right, right foot on the first beat etc.! Try it, it's harder than you think! It'll take about two weeks for you to remember to start counting on the right and some three months until it starts to be as easy as the left foot beat.
Here's the carrot: Making the right thing as natural as the left makes your brain grow new neural pathways which will serve as a reserve in case the previously used pathways fail, either because of an injury or a memory disorder like Alzheimer's.