Warming up for running by just running at a slower pace is pretty much the rule of thumb, with the big takeaway being to not stretch before running. Stretching cold muscles can lead to muscle injuries and doesn't prep the body for the upcoming work of actually running. However, an active, or dynamic, warmup does. Think leg swings, walking lunges, and planks for core activation. Check out this prerun warmup to learn what you should do before hitting the pavement.