Both in and out of the gym, military style boot camp workouts are popular for good reason.
"I really like boot camp because I think probably one of the most important things to do is always change up your workout. Always shock your body, because after about three weeks your body gets used to it," said personal trainer Erin O'Brien.
O'Brien gave us a handful of ideas to keep brain and body working hard.
In one partnered up workout, one person dips and works the upper body, while the leg holder gets quads and glutes working. Another idea is to take your running program in a different direction. Literally.
"A lot of people go outside and just jog. I really think that they should switch it up- they should sprint, they should do directional changes," said O'Brien.
Or people can perform a plank on a ball and change up the feet to challenge the core and upper body even more.
Catch and release with a medicine ball is a great way to stay motivated and accountable to your routine.
Adding fitness toys can create fun and burn loads of calories. For example, you can do double right hooks on weighted ropes or use an elevation system to do suspension planks with one-legged stand up return or partner lunges.
The possibilities are endless. Most of the moves ask you to buddy up.
"It just helps kind of push you, it helps push both people. If you're just working solo, sometimes you can only go so far. If you have a buddy there who's kind of spurring you on, it gives you that little extra push, to go that extra little mile," said fitness trainer Mike Donavanik.
Donavanik said it also works the other way around.
"But then if your buddy isn't motivating you, it's your job to motivate him. So you still need that internal motivation. You can't just rely on someone else," said Donavanik.
O'Brien has a series of DVDs and also works in the Burbank and Pasadena area.
Donavanik trains in Los Angeles and teaches a "Training Day" workout at Crunch in West Hollywood.