I've already talked about this first one so many times that you are bound to know what it is. MyFitnessPal. I use this every single day without fail. It took some time to get used to logging everything I ate every day, but I think I'd really struggle to keep track without it as it's so quick and easy, you can add friends and send little messages when they lose weight or hit a target, and you can log exercise too so you know what your rough net intake is. It also tracks your progress so you can see how far you've come, I've found it so helpful.
Get Running C25K is the running app I've been using to build up my fitness levels, we've got a treadmill at home and I've been following the app and found it so useful. It's hard enough to be challenging, but whenever you hit a new running time it's such a great feeling, and you can use the app to see how long it'll take until you'll be running 5K. I do tend to do more than it recommends as I only have one rest day between runs, but at the moment I've had a week off to rest my old lady knee and I'm really missing it! This is one of the few apps that lets you play your own music at the same time without interrupting you every ten seconds, although you can allow it to let you know how long you've got left in each section at different intervals.
30 Day Challenge apps are something that's quite new to me, I've downloaded the 30 Day Abs, Squat and Push Up challenge apps and am on day 8 with them. At first I wasn't overly convinced they were going to do anything but I'm persevering with it and I'm already noticing a difference, my stomach is getting flatter and stays flatter, I can actually feel my stomach muscles aching throughout the day as each day gets harder so it's always a challenge. The squat one is insane, but as I spend most of my day sitting down on the phone I thought I'd better do something to combat it! After a few days you'll do 50/75 squats without having to pause to console yourself halfway through, so I always like to think of that as an achievement. Push ups are not my friends, though. It starts of with 2-3 push ups, but they aren't the girly ones and I really cannot do push ups to save my life. It's ridiculous. Surely I should be able to do them? I've been doubling the amount it says to do and just doing girly ones instead, I'm hoping one day I'll be able to tackle proper ones!
Do you have any other health/fitness app recommendations?