6 ways to use your kid's old bedroom

Add a home gym

You packed the baby off, now it’s time to turn his room into a home gym so you can unpack some extra weight.

Swap your child’s bed for a Murphy bed, futon or sofa bed to gain room for a stationary bike and a treadmill or elliptical. Pick up used equipment on Craigslist.com or Freecycle.org.

Put a flat-panel television on the wall to entertain you when you exercise.

When you child complains that you’re a terrible person for making his room into a gym, remind him that it’s his fault you gained the weight. Offer to turn his room back into a bedroom if he pays for you to get liposuction once he has a real job.

Estimated cost: $4,000 if you buy new gym equipment, 50-inch TV and a queen sleeper sofa; $2,000 if you opt for used exercise equipment.