Jenn, kudos on your walk. I have to plump up my veins for bloodwork, too, even when I consistently drink 64 oz. per day. But I do have large veins on top of my hands and it doesn't bother me if they resort to taking blood from there. Wishing you really good results.
Age 68, 5 feet tall
Highest weight ever in the fall of 2010 246 lbs.
FitDay starting weight 1/17/2011 240 lbs.
Weight 6/25/2014 233 that obviously included a lot of water retention
Weight 7/13/2014 224.6 with an eye on "Onederland"