That’s because some forms of exercise are more beneficial to a specific body part than others. For example, studies find that interval training is effective in improving your cardiovascular function by maximizing oxygen intake. Other forms boost mental health through their effect on neurotransmitters and other hormones.

Heart-friendliest exercises: To improve cardio health, start with 30 seconds of intense effort; 60 seconds of rest; repeat. Do it while walking, doing jumping jacks, swimming or taking an aerobics class. Initially, your goal during intense effort is to achieve 65% of your maximum heart rate (that’s 220 minus your age); later 80%. Ask you doc first what’s safe for you.

Mood-friendliest workouts: One large multicenter study found that team sports reduced the number of days a month that you may feel depressed by 22.3% when compared with not exercising at all; bicycling cut it by 22%; aerobic and gym activities by 20%. Forty-five minutes two or three days a week conveys those benefits.

Your bonus: Mixing up your exercise routines lets you choose what suits your mood, making it easier to achieve the goal of working out five days a week.