A celebrity trainer reveals one thing you should do instead of working out harder

With the rise of boutique fitness studios like SoulCycle and CrossFit, it can be tempting to get on board with whatever the latest fitness trend is.

But working out can be dangerous if it's not done right.

Anna Kaiser, who has trained celebrities like Kelly Ripa and Sarah Jessica Parker, recently told The Cut that working out too hard is never a good thing.

"You can tell if you feel like you are unable to recover from the workout you had. It's still hard to breathe. You don't have energy. You are sore instantly. You just can't seem to get enough water. Then it's too hard. I don't think that anyone should be working out more than 60 to 90 minutes, four to five days a week," Kaiser told The Cut.

Rest is crucial. In fact, she told The Cut that sometimes, sleep is actually a better choice than waking up for that crack of down workout.

"Sleep more. I don't think anyone understands how important it is," she said. "If you have a choice where you've only been sleeping five or six hours and can sleep an extra hour or work out, sleep an extra hour."

When it comes to workout out, mixing it up is key. In an interview with Business Insider, Kaiser recommended taking a mix of classes and wearing a heart-rate monitor so you can see how hard you're working.

For Kaiser's full interview with The Cut, click here.