I've been reading up on how to overcome procrastination, and the main case study was a very overweight and overworked mum with a full time job. Instead of saying she should work out 30 mins 3x per week, the doc asked her to exercise (fast marching or star jumps - something to raise heart rate) for one minute during commercial breaks while watching TV. Just one minute a day.
She built up from there.
So I suggest start with something so unbelievably easy to achieve that you just can't fail: one minute marching, once a day for a week, then two minutes, or every ad break.
Decide to be a tiny bit more physical in your daily life. Put plates and glasses on higher or lowest shelves so you have to stretch and squat to reach them. Always squat down properly when you take washing out of the machine or unload the dishwasher etc. those squats add up in a day - you'll have done 20 a day easily and at the end of a single week, you notice it.
Always climb stairs in shopping centres and at work. Just one extra flight, if you get breathless, then keep adding a flight until you never use escalators or lifts.
Be the first to answer the door and reach for the phone. These sound like nothing but lots of tests reveal the really skinny people who apparently eat what they like and never get fat have that perpetual motion thing going. DS1 has. he stuffs his face and is skinny. DS2 is very static and eats the same or less but is pretty cuddly. The difference is, one curls up to watch tv and doesn't move a muscle. The other wriggles and fidgets and gets up to fetch water, answer the phone, the door, fetch snacks for others, go to the loo etc, that's a couple of hours either constant movement or no movement a few times a week, and it really adds up.
Final top tip: when you have a snack craving between meals, drink a big glass of water first then count to 50. If you still have the craving drink another glass of water. If you still have the craving, eat. But chances are, you won't.
I've lost 7lbs since October without dieting by doing this stuff. Not a lot, but given that I've chomped my weight in chocs and marzipan, not bad either.