If you're on a fitness kick, your smartphone can help you every step of the way.
RunKeeper and Sports Tracker use GPS to track you as you exercise and they're both available for iPhone, Android and Windows Phone 7.
Simply tell the app what activity you're doing, press go and then slip your phone into your pocket or an armband. The app does the rest - timing your daily run and plotting your path on a map so you can look back to see how you've improved.
As the name suggests, RunKeeper was first developed with a focus on running. This includes interval training, with a voice telling you when to speed up and slow down. It has evolved into a general fitness app that tracks a range of activities, both stationary and on the go.
It's also easy to share your results, keep track of your friends and even create virtual running teams. RunKeeper's HealthGraph focuses on your general wellbeing - analysing your exercise, weight, diet and sleep patterns.
To help with this, HealthGraph can talk to a range of fitness gear such as heart-rate monitors, sleep monitors and wi-fi-enabled scales.
Meanwhile, Sports Tracker focuses more on the social aspect of exercise, making it easy to discover other users near you as well as find your friends via Facebook. But you won't find the wider health features of RunKeeper.
If all you want to do is share your running results with friends, then Sports Tracker might be right for you, but if you're on a more general health kick, you'll probably appreciate RunKeeper's advanced features.