When it comes to fitting fitness into your schedule, it helps to make it fun. If you enjoy working out, you'll be more likely to keep it up, which can lead to a healthier and fitter you. One way to ramp up your workout fun factor is partnering up. Joint workouts allow you to catch up with a friend while burning calories or even make new friends in a dynamic and motivating setting. Some personal trainers offer group classes featuring partner workouts at special rates. Here are five exercises inspired by athletic trainers Sherri and Alex McMillan in IDEA Fitness Journal to get your blood pumping in tandem:

Push-up Contest

Some of the best workouts require no equipment. Challenge your partner to a push-up contest. Start at the same time and exercise at the same tempo--whoever lasts the longest wins. If one partner is considerably stronger, have the stronger partner do their set on a slight decline or do push-ups from the knees rather than the toes to level the playing field.

Partner Squats

This challenge also requires no equipment--just two motivated people. To begin, face your partner in a standing position and hold onto each other's arms. Each partner should then slowly squat backwards as though you're about to sit in a chair, keeping knees pointing ahead. Lower your bodies simultaneously until your upper thighs are parallel to the ground. Once in a comfortable position, begin to slowly push back up. Repeat eight times if possible, building up to 20 reps.

Oblique Crunches

While gym rats often perform basic crunches, many neglect their oblique muscles. Obliques are the muscles of your upper and side bodies that assist you in turning from side to side. To exercise your obliques with a partner, start by lying on your backs side by side. You should be facing opposite directions, with the outside of your hips almost touching. Slowly roll your torso upward, rotating towards your partner. When you reach the top of the "crunch," give your partner a high five with your furthest arm. Try to contract your abdominal muscles as you do this exercise on each repetition. Switch sides, working up to eight repetitions per side.

Tubing External Rotation

All that's needed for this joint workout is some resistance tubing, which you can find at most sporting goods stores. Look for the kind with handles on either end for the most effective grip. To begin, stand next to your partner facing the same direction. Each of you should take one handle of the tubing in your outside arm (the arm farthest away from your partner). Both bend your outside elbow at 90 degrees, anchoring the outside arm at your waist. Then slowly rotate the outside forearm away from your body before returning to the starting position. Repeat eight times for each arm.

Medicine Ball Sprint and Roll

A medicine ball can be a great workout tool for partners. You can purchase one inexpensively from a sporting goods store. Start by standing next to your partner, holding a medicine ball. Roll the ball forward diagonally so that it intersects the path of your partner. Your partner should sprint up to the ball and then roll it forward diagonally into your path. Then sprint forward to the ball and roll it back in front of your partner. Continue sprinting and rolling for up to two minutes.