I have to disagree a little with Trane. He does have a point about getting to the gym, but after many years pouring money into gym membership I decided that I'd give "working out at home" a shot.
I don't think you've necessarily disagreed with me there, you went from being a very active trainer at a gym to a very active trainer at home, that's a very different scenario to Jamie.
As I said, the real fundamental thing to do is finding something that you enjoy - it's so much easier to stick with something if you don't hate doing it (or even enjoy it!). Swimming, badminton, spin class, circuits, crossfit, kettlebells - there are a wealth of things you can try - even find out if a friend or colleague is willing to buddy up - again it's easier to find the willpower if someone else has a mutually reliant relationship with you.
Just please don't push yourself too hard from the offset, decide upon a sensible diet and workout plan, do not do anything drastic. This will ensure you make slow, steady - and most importantly - sustainable progress. Don't look at it is a quick weight loss or diet fix, change your lifestyle for the better.