Getting Back Into Shape

Last summer I weighed about 11.5 stone, pretty reasonable for my height. However this past year has seen me work my way up to 15.5 stone :( I spend most my time now just sat around and constantly feeding myself. My goal is to get back to where I was last year. Though I already tried earlier in the year to lose some weight I soon failed and the stone I had lost quickly found me again. Hoping this time I can actually get ALL the weight off and keep it off :)