The Y might be a source of support and good information for you. Perhaps you wouldn't trust the guidance of a personal trainer - they are not all equally helpful - but perhaps taking a class with seniors might increase your level of activity while you diet.
When I was in my 50s, I took a seniors exercise class at the Y, even while I took some other, more strenuous classes. The instructor had us sitting or standing, or even, in one man's case (back problems), lying on the floor, while we all did variations of the same exercises. I really liked it. It also worked some muscles that weren't worked in the other classes I took