Stuff envelopes for a charity. Whatever you do, bring your children along and let them participate with you. You'll not only spend time together, but also teach a valuable lesson about helping those in need. Instead of dropping my children off at the child-care center of a club, I do my workout with them. Strap on your tennis shoes and load the tot in the stroller and go for a brisk, long walk or jog.
Older kids love working out to tapes.
My kids particularly enjoy the Richard Simmons Sweating to the Oldies series. The music is fun and the moves are simple enough for them to follow along. Besides getting your workout in and enjoying time with the kids, you set an example of good habits and help your kids appreciate lifelong health. In fact, if anything, our kids show us what's important and insist that we slow down and enjoy life.