I did a 4.8 mile walk/run today. I was cold for the first mile or so, then warned up fast. I'm trying to shave a few more seconds off my pace, so I decreased my walking intervals from 3.5 minutes to 3 minutes. I feel the difference in my breathing, but my legs and feet are taking the change well. I hope to get down to 2.5 minute walking intervals by my next half marathon at the end of May.