Antigua is one of the best-preserved colonial cities in the Americas — cobblestone streets, colorful facades, volcanoes on the horizon. It's a city that was built slowly, one stone at a time.

That's exactly how today's workout builds. Start small — 2 squats, 2 push-ups. Add 2 more each round. Progress builds slowly, then all at once. You have 20 minutes. See how high up the ladder you can climb.

Every rep you add is proof that you're capable of more than you started with.