Brain injury guy here again. I started walking in May of this year. 1 mile was sheer pain. By September I was up to walking 200mi. Per month. In October I ran (shuffled) my first mile. On 11/4 I made 3.1 miles (some walking) in 42 mins. Today I was sub 37 for 5k, and I am down 106lbs. You can do it.