I've lost 2 stone and kept it off for many years just by incorporating exercise into my day.
If there's any way you can walk to the yard regularly then I would try and do that, I don't know how far your yard is however or if it would be practical for you to do this.
My yard is to far for me to walk to its 8 miles from the City but one day it could be cycle able...I used to cycle 10 miles a night after work.