Parents need to encourage their children to warm up properly and stretch before each activity and teach them never to play through any type of pain or make winning the reason for playing any sport. Let them choose the activity and keep the focus on having fun.

To keep kids moving, the American Council on Exercise suggests ten, fun fitness summer activities.

Soccer This highly active game involving both agility and teamwork has grown increasingly popular in the U.S. in recent years. To keep kids injury free, be sure they are geared up in appropriate protective equipment, such as shin guards. Soccer players should also wear shoes with cleats or ribbed soles to prevent slipping.
Martial arts With a variety of forms to choose from, martial arts are a great way to get kids involved in a sport that involves strength, coordination and mental discipline. Proper training and equipment to prevent injury are a must.
Bike riding Bicycle riding is a fun activity for the whole family. Experts suggest children ride on sidewalks and paths until they are at least 10 years old, show good riding skills and are able to follow the rules of the road. Helmets, of course, are a necessity for both children and adults.
Swimming Nothing beats splashing around a pool with friends, and swimming offers the benefits of a full-body workout for both young and old. The American Academy of Pediatrics recommends swimming lessons for children ages 4 and up, although classes are available for babies and toddlers as well.
Basketball Whether it's a round of HORSE, a game of one on one, or a full-court competition, basketball is ideal for developing hand/eye coordination and teamwork. Encourage children under the age of seven to use a smaller foam or rubber ball, and lower the height of the basket if possible.
Obstacle courses Challenge kids to use a variety of different skills by setting up an obstacle course at the park using playground equipment or other items, such as jump ropes, balls and cones.
Dancing Whether your kids like ballet or hip-hop, dancing encourages them to be creative and move their bodies freely. For video arcade fans, an innovative new game challenges opponents to follow a dance routine while watching the video. Kids can spend time learning new moves while also getting a great workout.
Board sports Whether snowboarding in the winter, surfing in the summer, or skateboarding year-round, kids love to be on the board. Injury risk, however, is higher for these sports. For both snowboarding and skateboarding, kids should wear helmets to prevent head injuries, and surfers or boogie-boarders should always be accompanied by an adult.
Jumping rope Jumping rope is still a favorite on most playgrounds. Whether alone or in a group, jumping rope challenges both coordination and stamina.
Ice-skating/inline-skating Ice-skating, inline-skating and hockey can be both fun and safe as long as appropriate protective gear such as a helmet, wrist guards and kneepads are worn. Hockey players should wear a helmet with foam lining and a full-face mask, a mouth guard, pads for shoulders, knees, elbows and shins, as well as gloves.