Whenever you're doing something that does not require use of your hands, turn them so that they're palm-side up. You also can do it while standing or walking, leaving your arms down at your sides and turning your palms so that they face outward in the direction you're facing.
Doing the palms up consistently helps your body to correct the posture by itself.
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Set a timer for 10 minutes and complete the circuit as many times as possible with little to no rest over the course of those 10 minutes.