A simple routine of push-ups, squats, sit-ups, lunges, and step-ups will help you stay strong, mobile, and avoid muscle injury as you grow older. Keeping active and incorporating these activities into your daily routine (considering that you're always on the go and have no time for a workout session) will also keep your metabolism active and keep you away from unnecessary weight gain as you age. Strength training and resistance training are vital for any person and they will prevent ailments and other annoying inabilities from springing up later in life.