Cost: $10 a month, $42 for six months, $60 for a lifetime subscription
If you're being strategic about using walking for weight loss, then Weight Loss Walking by Verv is for you. There's a three-month training program for various levels (both indoor and outdoor) that can help you increase pace and steps and reach your goals. You can also map your walks with GPS, listen to audio instructions to each training, and get detailed stats. Plus, you'll get dozens of tips on walking, healthy eating, and changing your lifestyle.