1. Ear Warmer
In the cold weather, fit girls need something to keep their ears toasty warm! This Run With Me ear warmer by Lululemon will do just that. It's comfortable, functional, and cute. It's also snug enough that you could layer it under a hood or hat.
2. Thermal Tights
I have a non thermal pair of tights just like this pair of Nike Element Shield tights, only mine aren't thermal (because I bought them in Texas where people don't need thermal tights haha). If your fit friend lives somewhere cold, she will love a pair of thermal tights that she can run in. Under Armour also has tights that have their new Omni Heat technology that reflects your body heat back towards yourself. These could be layered underneath normal running tights to keep you warm.
3. Softshell Jacket
These things are lifesavers. They're light, but wind resistant and super warm. I love running in my North Face jacket. As a bonus, the shape is really flattering and slimming.
A girl needs some music motivation to push through a tough HIIT, keep pace in her run, and keep calm during her yoga sequence. I like these Yurbuds headphones because they hook behind the ear, keeping them from falling off. They're also pretty affordable and cute!
5. Fitness Tracker
These things are all the rage these days. Matt and I are actually going to wait until 2015, and buy one another the Fitbit Charge HR as a belated Christmas gift for one another. It tracks steps, stairs, heart rate, sleep, and lets you know who is calling you!
6. New Shoes
Whether your girl spends most of her time in the gym lifting or she's more of a street running girl, she would probably always be happy to have a new pair of shoes! I have a pair of Nikes for the gym and I just bought a new pair of Asics for running. If you're going to get her running shoes, you may want to casually ask if she pronates/over pronates when she runs. That will help you to know if she needs a more structured shoe or if she could run with a regular shoe.