Sweating it out in the gym is a known de-stressor. Harvard Medical School has shown that aerobic exercise helps curb stress hormones like cortisol and adrenaline (as long as you're not overdoing it), while also flooding your system with feel-good endorphins. It also ups the calming, good-mood brain chemicals serotonin and dopamine. So while exercise itself is actually putting low-level physical stress on the body, it can be pretty mentally relaxing.
Get down on all fours with your knees placed directly below your hips and palms placed directly below your shoulders. Now, raise your right arm forward and stretch your left leg backward at the same time. Create a tension in your back by flexing your foot. Hold the position for a few seconds and then come back to the starting position. Repeat the same using your left arm and right leg. Repeat 15 to 20 times on both sides.