If you haven’t looked at a kettlebell for a decade, we’ve got news: They’re back. No longer relegated to the far corner of the gym, kettlebells are taking a prime place in our at-home workouts. They don’t take up much space and they’re versatile. Use a five- or ten-pounder to add weight to squats, lunges, and upper body workouts. Or pick up a fifteen- or twenty-pound one for kettlebell swings—as great for cardio as they are for strength-building.

• Cast-iron