While life may be going on smooth and you are quite comfortable with the way things are working out around you, everything can change in a snap.
Life or more precisely, the world, is ever changing. It doesn't stop for anyone. Not you, not me.
Situations change. People change. You or your goals can change.
Instead of sitting back believing that you have your life sorted out, be prepared for change. It can happen anytime. Maybe tomorrow, or maybe a month from now.
Don't let change catch you off guard. When situations are changing, make sure you say "Bring it on, I am ready!".
If someone moves your cheese, stop hoping that they will place it back in the same place. Go out looking for some new cheese.