Once again, 30-day fitness challenges are all the rage on social media. Whether it's a family workout challenge, a flat-abs-in-30-days challenge, or a popular 10-minutes-of-yoga-a-day-for-30-days ...

The Sofa Squat challenge is for anyone who ... Start with at least 10 Sofa Squats a day, then when you feel comfortable move on to 20, then 30, then 40, building up to 100 over the 100 days.