So I've been walking/jogging for the past month or so. Nothing crazy just about 3miles a day. I'm a beginner at all of this but would love to do this everyday. I have a pair of running shoes but I get a huge blister on the back of my right heel every time. I wear a size 8-8.5. These particular shoes are 8.5's. I know my right foot is a tad bit smaller than my left but how do I stop this? I've tried putting large circular cosmetic sponges in the right shoe but they slip out. Any advice is helpful. Also how can I increase my endurance and push for actual running? Thanks ladies!