iPhone: Moves is one of the simplest activity trackers out there for logging steps, bicycling, running and location automatically. Today, it gets an update that improves battery usage, makes it compatible with iOS 7, and adds support for the iPhone 5s M7 chip.
The big update here is that Moves now has a battery saving mode, which should boost your battery life significantly. Moves now also supports the M7 chip in the iPhone 5s, which should help with battery life as well.
The update is free for existing users, but it does cost $1.99 if you're buying it for the first time.
Moves ($1.99) [iTunes App Store]