If you can nail a 90-second plank after 40, your abs (and waistline) will thank you. Forget endless crunches—this one move fires up your entire core, glutes, and shoulders, and actually tightens your midsection. Hit that 90-second mark and you’re in elite territory for core strength and fat burn. Not there yet? Start with shorter holds and build up. Your posture, metabolism, and jeans will notice. Who’s up for the challenge? #Fitness #FitnessChallenge #PlankGoals