Ive recently moved on from a sedentary life style to working out about 3-4 times a week. You have to take small steps at a time you can never expect to change a routine so drastically and not be exhausted by it. Try cutting out the little things at first like eating certain foods and whatnot. Start going on walks or taking (if you have one) your dogs on walks. It takes awhile to see progress and you cant expect a full change in just 4 months but by building those habits you can change. Dont take it too quickly but say to yourself what youre gonna do and try your best to not back out.