Sit-ups are a classic core-strengthening exercise, great for working the abdominal muscles near the surface of your torso.

Jumpstart your fitness routine with this monthly workout plan that prioritizes both physical and mental health.

By day four, I was feeling it. Laughing, bending down, and just getting into position for the workout had my abs reminding me of every rep. By the seventh day, my core wanted a day off, and I had ...