Move Your Way provides an interactive tool to help you find the activities you can do at home or in the gym.
This site provides exercise testing resources.
ACSM provides books and resources to increase your knowledge about aerobic training.
Topend Sports provides a wide range of science backed information about sports, fitness, and nutrition.
Human Performance Center is your link to a wide range of resources to improve your fitness for people who serve in the armed forces.
Endurance Exercise (Aerobic) resources to get you started.