I assume a 5 day split is overkill, right? If your goal is simply health oriented, what sort of exercise regimen is best? 3 resistance training days per week where you hit all muscle groups?

Also, what type of aerobic activity is best for the heart long term? I read that marathon runners develop stiffening of parts of the heart muscle and it isn’t good. Is it better to reach a moderate heart rate for medium length of time, or use a method like HIIT where you reach your peak/have an intense heart rate but for short bursts?