The best part of iFitness, though, is a large database of images that show steps on how to perform various exercises with equipment, activities and stretches without causing injury.
Not all apps on this list are about eating and exercise. When it comes to your health, knowledge is power. The free WebMD Mobile app, based on the popular WebMD website, should be on every iPhone--at the very least for its first aid information, which does not require an Internet connection.
A medical encyclopedia at your fingertips, WebMD Mobile gives an overview of various medical conditions, symptoms and links to articles. You can also get information in reverse order by inputting your symptoms or searching drugs and treatments.
WebMD Mobile taps into the iPhone's GPS and provides local physicians, pharmacies and hospitals, as well as directions.
Many iPhone apps specialize in activities, such as tennis, soccer and even golf. RunKeeper Pro ($9.99) is a bit on the costly side, but if your hobby is running, you'll want it.
The best thing about RunKeeper Pro is that it uses a lot of the iPhone's capabilities. Using GPS, the app tracks how far you've run and how long it took, and then calculates your speed and calories burned. There's even a map of your run in progress. You can share your stats with friends and fellow runners on Facebook and Twitter. RunKeeper Pro supports geo-tagged photos and iPod integration.
iPhone apps for other activities include: Cyclemeter GPS ($4.99), Yoga Stretch ($.99), and Navy SEAL Fitness ($1.99).
An usual app rising in popularity in the App Store's health and fitness category is Sleep Cycle ($.99). Just launch the app and place it near you when you sleep. The app uses the iPhone's accelerometer to monitor your movements during sleep and charts the rhythmic sleep-phase pattern of dream state (that is, light sleep) to deep sleep to dream state again.
Then the app will gently wake you with soothing sounds inside a 30-minute time period of your choosing at a moment when you're in light sleep. No more getting jolted from a deep sleep by a buzzing alarm clock. The end result: You wake up refreshed and ready to go.
A good night's sleep is important for good health, but so is how you wake up.