It doesn't have to be something you have a lot of experience with. It might be something you've read about, but never had the opportunity to try. Maybe it's history or scuba diving or the Everglades. Look at your values. For many people, the opportunity to work with Habitat for Humanity building houses during the summer is more fulfilling and relaxing than spending two weeks at the beach.
Many people become stale at work.
Their jobs don't pull anything new from them. Find a way to pursue a creative outlet, especially one you have wanted to try, but never found the time for. Sometimes the easiest thing is to throw all of your energy and personal resources into work. Paying attention to a long-neglected spiritual self can often bring more renewal and energy than standing in line at Disney World. The most important thing for families is to work on vacations together.