I've extracted this from this weeks parkrun news letters. It shows what running can potentially achieve for you.
Hi parkrun UK
At the beginning of 2014, at just under 20 stone I managed to creep under 30 minutes for the first time in a while after three weeks training. By the end of the year I managed to lose seven and a half stone and run under 18 minutes. Looking forward to parkrun each week was a huge motivation in helping me improve my running and lose weight. I am lucky enough to have seven different parkruns within 30 minutes drive of my home in Newbury to keep things interesting, and rotated a different run each week. It helped me achieve 31 PBs throughout the year over the seven different courses.