Roller skating/ Rollerblading: Roller-skating or Rollerblading can be done indoors or outdoors, either way, proper protection gear must be worn at all times (even big kids can fall down, i.e. me). If the summer heat is too much to bear, look up the nearest Roller-skating rink and schedule a few hours for yourself and some friends. If you are feeling adventurous and own a pair of either skates or blades, find the nearest paved trail and have at it. Pool Volleyball: Maybe it's the cool, refreshing pool water that makes Pool Volleyball more fun than regular volleyball, but after a game or two the resistance the water creates around your body will help you burn off some calories. Pool volleyball can also be less competitive than regular volleyball, and it can take up an entire afternoon at a BBQ with the family.
Badminton: Less intense than tennis but just as fun when you set up a makeshift court in your backyard. Badminton is a great way to work out, or just have fun in the summer months because the game will have you running back and forth and using your upper body to hit the shuttlecock (birdie) over the net. The games mentioned above will keep you on the move this summer regardless if you are athletic or not.