Hard work

Last night was a little bit strange, I went out for a run about 4:30 in the evening and after about 1 mile I was really struggling so I decided I would only do my 2.1 mile run. I picked up the pace a bit to compensate for the short run and managed it in 20 minutes (which I was pleased with) but I really had to push myself for the last quarter mile. I had been out with the kids all day and we had walked about 3 miles. I don't know if the walking had some affect, or maybe I was tired from last nights 3.6 mile run or a bit of both?