I do weight a lot for my height but people are genuinely shocked when I tell them my weight so I don't think I look my weight (12 stone) - and wear sizes 12/10.
A job has just arisen near me, part-time in a store which sells clothes for running, yoga, tennis etc - they even have exercises classes in the store during the evening. (You can attend for free if you work there too)
I do have sales experiences but I just think even if I did mange to get an interview I'm hardly a size 6/8 which they would probably prefer so my experience is pretty irrelevant.