As part of their training, Navy SEAL candidates swim lots of miles, sometimes in the middle of the night and sometimes with their hands and feet bound. Fortunately, you don’t need to go to such extremes, but former SEAL Stew Smith believes swimming is an excellent way for you to build stamina. He says, “Swimming after weight training is a great way to add endurance, which will really help you in the fourth quarter of your big game.”

To get your water workout on this summer, follow these tips.

Swim at the End of Workouts

Smith recommends swimming after your regular workout, when your muscles are already tired. “For me, swimming isn’t a replacement workout—it supplements what you’re already doing in the weight room,” he says. “Swimming is a great non-impact cool-down that makes you feel great after a hot, sweaty training session.”

Be a Screwdriver, Not a Seesaw

Most beginning swimmers pop their head out of the water to breathe, but that pushes their feet down and slows their momentum. Smith instructs athletes to keep their heads down, turning their bodies like a screwdriver (rather than a seesaw) and spinning to the side to breathe. Don’t worry about having perfect form. In fact, since they are less efficient with each stroke, football players often get a tougher cardio workout from a short swim than the athletes on the swim team.

Invest in Flippers

For a fantastic lower-body workout, propel yourself across the pool using only flippers and flutter kicks. Smith recommends starting with inexpensive slip-on snorkel flippers. When you’re ready for a tougher challenge, invest in the long SCUBA fins the SEALs use during their training. The elongated fins create more resistance, so your legs have to work harder to push your body though the water.

The SEAL Swim Workout

Upper-Body Focus

• 3 minutes of swimming
• 1 minute each of Push-Ups, Planks and Sit-Ups

Sets: 5-10

Lower-Body Focus

• 3 minutes of swimming
• 20 Bodyweight Squats on the pool deck on odd sets, 20 Lunges on the pool deck on even sets

Sets: 5-10

Cool-down

• See how far you can swim in 15 minutes
• When you can swim for 15 minutes without stopping, increase the time to 20 minutes
• Aim to swim 1,000 yards in 20 minutes

No Pool? No Problem

If you can’t get to a pool this summer, try the following bodyweight workouts, which offer many of the same benefits as swimming.

Upper-Body Workout

• Max rep Pull-Ups
• 40 Push-Ups
• 1-minute Plank
• 400m Sprint

Sets: 5

Lower-Body Workout

• 20 Bodyweight Squats
• 40 Lunges (20 per leg)
• 20 Oblique Crunches per side
• 400m Sprint

Sets: 5

Take the challenge even further by trying another SEAL swim workout.