Hooray for warmer weather and hooray for running outside. If you're sticking to softer surfaces such as woodsy trails or grass to protect your knees, then you've got to be careful about injuring your ankles. The best way to prevent achy ankles — or worse, a sprain — is to strengthen them. Here's how:

• Do squats and lunges on a Bosu. The unstable surface challenges your muscles in new ways, thereby making them stronger and preparing your ankles for running on soft or uneven surfaces.

• Jump rope. It strengthens the muscles and ligaments that support the ankle.
• Do both tip toe walking and heel walks. Walking on your toes will strengthen your calves, and heel walking will prevent shin splints.
• Mobilize those ankles. Either write all 26 letters of the alphabet with each foot, or do ankle rolls. These little activities strengthen your ankles from a variety of angles and help the joints stay mobile as well.

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