Confession time: I haven’t been to the gym in five days. The first time I skipped my usual 7 a.m. call time was because I was in an Olive Garden-induced salt hangover. The second was because it was my birthday (a given), and the third was because I was too tired-slash-hungover from my birthday celebrations. And now, nearly a week of “good excuses” later, here we are.

Experts have already told us that you start to lose the mental motivation to get moving after only two skipped workouts. So the longer you go without hitting the weights, the harder it is to get back to them, which about sums up how I personally feel right now. But as I laid in bed this morning, ignoring my alarm and letting a 38 dollar fitness class go completely to waste, I got to wondering: If my brain was already feeling the fallout from so many skipped gym days, how long would it take for my body to catch up?

“Muscle strength will start to decrease after around three weeks, but it’s going to be affected by various factors. So it’s not the same for us all,” says FitHouse trainer Nina Marchione. Cue me breathing a big sigh of relief that my current gym hiatus won’t totally destroy the work I’ve put in for the last few months. “Your workouts may feel harder after only a week off, but the actual muscle won’t go away that fast.”

A 2015 study from the University of Copenhagen found that it takes only two weeks of skipped workouts to lose significant muscle strength. Younger people who were immobile for that amount of time lost one fourth of their muscle mass, while older people lost a third. “The more muscle mass you have, the more you’ll lose. Which means that if you’re fit and become injured, you’ll most likely lose more muscle mass than someone who is unfit, over the same period of time,” Martin Gram, PhD, researcher at the Center for Healthy Aging and the Department of Biomedical Sciences, told Science Daily when the study came out. So basically, the more muscle you’ve got, the more you have to lose when you stop working at keeping it strong.

“If you take off more than two weeks, your muscles fibers will start to lose mass and you will notice it,” confirms Gary Olson, DC, of the LI Spine and Sports Injury Center. But of course, he adds that “everyone is different and will respond differently.”

But with all of that in mind, it’s worth noting that rest days in general are super important—as long as you’re, you know, interspersing them with actual workouts. Pros agree that you should try to take at least one every week—whether it’s passive or active—in order to give your body time to properly recover, and ultimately, get stronger. In fact, according to Olson, if you’ve been working out for a while, you may find that you actually feel stronger when you come back after time off. As long as it’s been less than two weeks, that is.

Even if your muscles might be able to stay strong for longer than you’d think (two weeks seems like a pretty big stretch, no?), going back to the gym after taking time off may leave you more susceptible to injury. So, as with anything related to exercise, it’s important to listen to your body and take things at a safe speed—whether you’re amping things up or slowing them down to a halt.

If you can’t make it to the gym, take yourself for a run around the block—according to the longest-living people on earth, it totally still counts. And here’s exactly how much exercise you need to be doing to combat the effects of sitting all day.