Running inclines, either indoors or outside, is a form of resistance training and it will provide you with a chance to target muscles more deeply than if you just went on a flat run. Specifically hills target your calves, quads, hamstrings and best of all your glutes!
:: Because our hills look like this right now it's time to take them inside! ::
Here's one of my favourite treadmill hill sessions:
Warm-up: 5 minutes at a 7.0 mph
Then each hill for 5 minutes, if needed take one minute flat jog between each hill at a 5.0 mph
Hill #1: 15% grade (typically as high as it will go) at a 3.5 mph
Hill # 2: 10% grade at a 6.0 mph
Hill # 3: 5% grade at a 8.0 mph
Hill #4: 2% grade at a 10.0 mph
Make sure when you're done with the hill you take time to stretch your calves and legs! If you're not used to hills they can be really tough on your legs at first so be sure you're fully stretched out after!