Multiple studies show that increasing your physical exercise can also increase your happiness. There are dozens of apps and wearable technologies (like bracelets with sensors embedded inside) focused on helping you track, measure, and optimizing your health. For a great list of over 500 apps, check out the Quantified Self Guide and download some free apps along these lines to try for yourself.
To get you started, check out the Cardiio app. Born out of technology from MIT, the app measures your heart rate by pointing it at your face. Less light is reflected to your face every time your heart beats, and the biosensors in the tool use that to provide an accurate heart rate. Data can be shared via social networking channels, and insights about other people in your age/health range help provide a context for how you can improve your health.