MOST ATHLETES THINK of calisthenics as boring exercises performed while wearing military fatigues or middle school gym uniforms. Not surprisingly, most of us can’t summon much enthusiasm for such old-school movements as the sit-up and the jumping jack.

But those same calisthenics prescribed by generations of drill sergeants and gym teachers have been rebranded in recent years as body-weight exercises. Much of what constitutes CrossFit, boot camps, and obstacle race training is simply calisthenics, except with better marketing and packaging.

The word calisthenics comes from the Greek words kallos (beauty) and sthenos (strength). Indeed, there’s a timeless beauty to training for strength and flexibility via pushing, pulling, lunging, and lifting movements using little to no equipment. When performed in a continuous, rigorous fashion, calisthenics train up your strength and aerobic capacity.

And in an increasingly mobile, time-pressed culture, it’s important to have training options that can be performed anywhere, anytime and with little equipment. Good old calisthenics provide those workout opportunities. Here are four such calisthenics workouts.

1. The hotel room calisthenics workout

You have just 15 minutes in the morning while traveling, not even enough time to venture to the lobby gym. You have time for three sets of these.

Push-Ups (10)
Lateral Lunge (10 per side)
Plank (One Minute)
Squats (10)
Crunches (20)

2. The playground calisthenics workout

Calisthenics can involve minimalist equipment such as bars. If you have access to a park bench or pull-up bar, you can add to a basic calisthenic routine. Do three sets of 10 for each exercise.

Squat Jumps
Dips (on a park bench)
Calf Raises (on a step)

3. The beach calisthenics workout

As volleyball players know, playing in sand is more fun – but more of a physical challenge. Heck, most Navy SEAL training is on the beach. This three-sets-of-10 isn’t nearly as difficult.

Jumping Jacks
Mountain Climbers
Walking Lunges

5. The commercial break calisthenics workout

Next time your team calls timeout, knock out this three-set routine in front of the TV.

Push-Ups (10 reps)
Dips (10 on a sturdy chair or ottoman)
Plank (hold for 30 seconds)
Leg Raises (10 reps)
Squats (10 reps)

Pete Williams is a NASM certified personal trainer and the author or co-author of a number of books on performance and training.