To fire up your metabolism and shift fat burning into high gear, you don't need a ton of time. In fact, you can make it happen in as few as 10 minutes. Even better news: You can trigger this effect by strength training, running—even climbing stairs or pulling a sled. But, no matter which type of exercise you pick, the key is that you have to do it right (you must push to your max effort and get outside of your comfort zone). These five varied routines are guaranteed to get you there. 

Courtesy of Joel Sanders, trainer at EXOS.

Workout 1—DB complex

Do 5 reps of each of the following exercises without resting or setting the dumbbells down. Rest 1 minute, and repeat. Do 3 total sets.

>Snatch
>Squat to Press
>Bentover Row
>Reverse Lunge
>Pushups (hands on DB’s)

Workout 2—Sled push challenge

>Load a sled with two 45-lb plates on each side (180lbs total).
>Push the sled 40 yards. Pause, then push back 40 yards to the start. Repeat as many times as you can in 10 minutes. If you can do 8 40-yard trips in 10 minutes, you are a beast.

Workout 3—Treadmill ramp sprints

>Set treadmill at 10.0 incline.
>Start at 7-9mph, and run for 30 seconds.
>Jump off, and rest for 1 min.
>Repeat, increasing the mph by .5 for each 30-second sprint
>Follow this pattern until you max out on your speed.

Workout 4—10-1 ladder

>Start with 10 pullups, and superset with 10 dips.
>Then do 9 pullups, and superset with 9 dips.
>Continue working your way down until you finish with one pullup and one dip. 

Workout 5—Tabata slam

>Do as many medicine ball slams as possible in 20 seconds.
>Rest 10 seconds.
>Do as many burpees as possible in 20 seconds.
>Rest 10 seconds.

>Repeat for 4 rounds total.
>Rest for 2 minutes.

>Then, on a stair-climber machine (or actual stairs), climb as fast as you can for 20 seconds.
>Rest for 10 seconds.
>Repeat for 8 total rounds.