So you’ve decided it’s finally time to get serious about getting in shape. Great work! But just because it is the time doesn’t mean you always have the time. There are tons of yoga, pilates, cardio and strength training workouts available on YouTube (that’s right, no gym necessary), but if you’re a busy #girlboss, you need a routine that’ll let you exercise your multi-tasking skills. That’s where HIIT (high-intensity interval training) comes in. HIIT workouts involve a series of hardcore, all-out cardio and strength moves in short intervals, with active recovery periods in between. The idea is that your heart rate stays elevated, and your body burns more fat in less time. We’ve narrowed it down to seven you can do in just 20 minutes. Try a different one every day this week!


1. Brutal HIIT Ladder Workout: Over 5 million viewers can’t be wrong. This is one of the most popular HIIT workouts on YouTube, period, and it’s easy to see why. You might be a little intimidated by the fact that it’s described as “brutal,” but suck it up! We promise — this is what you came here for. (via Fitness Blender)


2. 20-Minute Bikini HIIT Workout: The “bikini body” cliche might make you roll your eyes, but stay with us — the last thing you’ll be thinking about during this intense workout is frolicking around on the beach. The POPSUGAR Fitness team doesn’t mess around, getting right into it with variations on key moves like push-ups and gate swings that keep your muscles guessing. (via POPSUGAR Fitness)


3. 20 Minute HIIT Cardio Workout: If your primary goal is insanely toned legs, do not sleep on this video. The moves are deceptively simple, but you once you get going, you’ll realize just how brutal squats and lunges can be when integrated with jump moves. (via FitnessType)


4. Can You HIIT Like a Girl?: We’ll admit, this video first caught our eye because we love a good pun, and all the better if it subverts a sexist cliche. But by the time we started the workout, we definitely weren’t laughing anymore — because we were too busy trying to catch our breath. The moves in this HIIT workout are pretty challenging, especially those multi-move burpees you get into right from the jump. (There’s a pun of our own for you.) (via FitnessBlender)


5. Tabata Best High-Intensity Fat-Burning Cardio Workout (HIIT): If you don’t mind things getting a little repetitive, this routine is easy to follow and crazy-effective. You only go through four basic moves (high knees, burpees, squats with a weight and mountain climbers), but there are eight rounds of each.


6. 20-Minute High-Intensity Workout: Celebrity trainer Astrid Maguire is a favorite guest-host on POPSUGAR Fitness, and it’s easy to see why she’s so frequently asked back. This workout is the perfect balance of playful, powerful and plyometrics. (via POPSUGAR Fitness)


7. Low Impact Beginners HIIT Workout: If you want to ease into HIIT (or go a little less hard at the end of a week full of it), try this quick, no-equipment routine that takes you through a ton of foundational moves. (via TheBodyCoachTV)

Show us your sweaty selfies post-HIIT workout by tagging us on Instagram + using the hashtag #BritGoesHIIT!