As a runner, you already know you should be stretching more, so I'm not even going to go there. I'm just going to present you with the most amazing Sun Salutation variation ever, which has been specifically designed with your runner body in mind. This sequence is full of hip openers, hamstring stretches, quad and glute toners, and lower back lengtheners; if you only do one thing today (besides go for a run), make this it. Repeat this sequence at least twice before or after a run, and you'll notice a difference.
Note that this sequence flows like regular Sun Salutations, moving from one pose to the next with each inhale and exhale. If you prefer, you can hold each of these poses for five breaths for an even longer and more intense yoga session.