“What a workout!” These words are frequently uttered (or thought) by many a grandparent after a day — or more! — of blissfully babysitting a new baby or toddler in the family. Moms and dads often feel the same way. Two fathers, in particular, have taken the sentiment a step or two further by turning their baby time into personal fitness routines that benefit dad while entertaining baby. These fathers have even turned their baby-inspired workouts into books.

Matt Swenson, a writer for the Washington Post, is a new father who’s discovered a whole new appreciation for bouncy exercise balls. Seems his 5-month-old daughter finds the bouncy ball the perfect spot for a nap, as long as daddy keeps her in his arms and keeps on bouncing.

During one of their bouncing nap sessions, the notion that he could be working out while his daughter slept got the best of him. He turned to an electronic activity tracker that fits the wrist to see if he was, indeed, getting any physical benefits from his daughter’s nap. He was. He was burning more than 100 calories during a single 30-minute nap.

Swenson writes about two other fathers who were compelled to write books about how they turned time tending their children into physical fitness workouts for themselves. There’s an awful lot of physical activity involved with the everyday interactions of a baby and these men simply made the most of the unavoidable.

For author Jon Finkel, kids are giant weight balls that are a lot cuter than dumbbells. In his book, The Dadvantage: Stay in Shape With No Sleep, No Time and No Equipment, Finkel, the father of two, says anything that requires a parent to pick up a child is a strength-building exercise. Do it repetitively and mindfully and 30 minutes holding a baby can be a 30-minute workout. He encourages dads to embrace their new reality and to remember to do some car-seat curls when running errands with the baby.

In his book, Baby Barbells: The Dad’s Guide to Fitness and Fathering, Jon Levitt says lifting 20 pounds of the baby while doing squats eliminates the need for weights while targeting all the right muscles. This father of three is also a naturopathic physician.

Mike Everts advises parents to lift and carry babies and small children correctly to reduce the risk of hurting themselves. Everts, the owner of a personal training center in Washington, DC, says bending over to lift the baby from any surface (bed, crib, stroller, etc.) puts too much pressure on the lower back and the shoulders. He advises squatting or kneeling down to baby level and using the legs and abdomen to lift the child more safely. Grandparents might benefit from Everts’ advice, too.

Source: Swenson, Matt. “Father figure: How to turn to parent into a  workout.” The Washington Post / Express. The Washington Post. Jan 28, 2014. Web. Feb 14, 2014.