Whether you’re looking to improve your health, shed fat, add definition, or just get super strong, strength training is hands down one of the best ways to spend your gym time.

In fact, when Harvard researchers followed 10,500 men over the course of 12 years, they found that minute-per-minute, strength training was better at fighting abdominal fat (a marker for overall health) than traditional steady-state cardio.

Meanwhile, a comprehensive review published in Aging Clinical and Experimental Research identified strength training as one of your best bets for increasing bone mineral density and strength—no matter your age.

And, contrary to popular opinion, cardio doesn’t have a monopoly on cardiovascular health. According to a review published in Current Sports Medicine Reports, regular strength training significantly improves blood pressure, cholesterol, and other markers of heart health.

Problem is, when you first decide to introduce strength training into your regular workout routine, a bunch of questions are bound to pop up: How often should I strength train? How should I format my strength sessions? Should I do total-body strength circuits or dedicate different days to different muscles?

Like in many things fitness, the answer is a resounding “it depends.” But by zeroing in on your goals, you can pinpoint the best strength-setup for you and your body.

If You’re Training For General Health

“Two to three sessions per week is a good minimum for staying healthy,” explains Minnesota-based exercise physiologist Mike T. Nelson, Ph.D., C.S.C.S. Men who strength trained three days per week improved their LDL, HDL, and total cholesterol levels, as well as markers of inflammation, according to one study published in The Journal of Sports Medicine and Physical Fitness. Your two or three weekly strength training sessions should be part of a routine that also incorporates other types of exercise, like steady-state cardio, high-intensity interval training (HIIT), and flexibility work, for well-rounded fitness, says Nelson.

When you lift less frequently, you’re better off making those strength training sessions full-body workouts, he says. Stick with large, compound movements such as squats, deadlifts, lunges, push-ups, and pull-ups to hit all major muscles. Spread your strength-training days out throughout the week, with a day or two for another type of exercise or rest in between each lifting session.

If You’re Training For Fat Loss

The ideal amount of strength training for fat loss largely depends on how much cardio you’re doing (whether steady-state or HIIT)—but you generally want to strength train as often as possible, without running yourself into the ground, Nelson says. One factor that might limit your weekly strength workouts? The low-cal diet that’s often part of a fat-loss plan may leave you with less energy for training, he says.

Given that, Nelson prefers to start weight-loss clients with three days of full-body strength workouts, plus three days of cardio per week. That might mean you lift on Monday, Wednesday, and Friday, and hit cardio Tuesday, Thursday, Saturday.

Related: This Is The Best Cardio Workout For Weight Loss

If You’re Training For Muscle Growth

If you want to maximize hypertrophy (a.k.a. muscle growth), strength training should be your primary focus all week long. If you’re trying to transform your bod with muscle, we’re talking to you. “The best results will come with strength training as much as you possibly can, as long as you are recovering from each workout,” Nelson says.

After all, a 2017 review published in the Journal of Sports Science concluded that your weekly training volume (or total number of sets, reps, and weight used) has the biggest effect on how much mass you gain in any worked muscle group.

So how much can you handle? Brand-spanking-new lifting newbies should start with three days of full-body strength training a week. But people who have been regularly strength training for a while (say six months or more), can often strength train five or six days per week.

Since you want to rest any given muscle group for about two days before hitting it again, lifting five-to-six days a week requires some strategic workout structuring. That means focusing on different muscle groups on different days, says Nelson. You might work your back and biceps one Monday, legs on Tuesday, chest and triceps Wednesday, etc.

Keep track of your lifting performance, energy levels, muscle soreness, and mood to make sure that you don’t push it too hard, he says. Any issues in these areas  suggest that you need to dial down your weekly training frequency and/or volume.

Related: 5 Signs You Need A Day Off From The Gym

If You’re Training For Strength

Research from Arizona State University shows that strength-training newbs reap maximal strength gains by training each muscle group three days per week. Veterans, though, do best working each muscle group two days per week—as long as they lift closer to their 1RM (a.k.a., ‘one rep max,’ or the max amount of weight you can lift for just one rep) during each strength sesh. That means fewer reps per set than if you were lifting for max muscle gain.

To hit each muscle group two to three days per week, try dividing your workout routine into upper- and lower-body days, says Nelson. That might mean alternating between upper-body and lower-body Monday through Saturday and resting on Sunday. You can also break up your upper-body days into push and pull days to keep things interesting. You might focus on moves like the bench press on ‘push’ days and on moves like pullups on ‘pull’ days.