These two best friends started a fitness revolution for women on Instagram

Two women have inspired hundreds of thousands of women to get off their butts and start living healthy lives by working out and eating nutritious food.

And it's all thanks to Instagram.

The best friends have started a #ToneItUp community, where they teach women how to work out and what to eat.

They also make it really fun - it's hard to not want to become friends with them when you watch their YouTube videos and Instagram uploads.

Now they have books, a show on Bravo, and have made countless appearances on television and in magazines, all while traveling all over the world to meet their fans and supporters.

Meet Karena and Katrina and the #ToneItUp community.