Hi mjchik!
I don't know if you're going to get that instant switch going on in your head but I think your idea of testing the water might be better. That sounds like starting with some small changes, getting used to them and then getting in a little deeper when you're ready.
Maybe a good start might be to think about what you're eating and how much, and ask yourself some questions like what can I eat less of, what can I find better substitutions for, what can I add, what can I give up and not really miss all that much? That and some moderate exercise is what helped me lose 17 lbs these past two months. For instance, I like sandwiches and wasn't going to stop eating them. So, I just came up with ideas for lower-calorie sandwiches, like using lo-cal bread and mayo, re-discovering that I like turkey slices, lol. I love cheese sandwiches, I just don't have them as often anymore and that's okay, that's a change I'm perfectly fine with. I like salty snacks, so now I have lower-cal pretzels and the 100-calorie packs (which are great for me with portion control and all). I've increased my fruits and veggies, I've eaten a lot of the lo-cal frozen dinners and I just discovered Lean Pockets and love those, lol.

I'm not eating exactly the same foods I was a couple of months ago but I am eating things I like and that's part of why it's been working for me. And, true, part of it, in addition to changing around some food choices is mental. Your mind's gotta be on board with it, your mind's gotta kick in and say stuff to yourself like, you don't need to buy that big bag of Chips Ahoy, look for something else you can have in the house that you can still enjoy. If you try to go cold turkey (pardon the pun) right off the bat (sorry for mixing metaphors), you might risk find yourself feeling frustrated or deprived and you know what that leads to.
As for the exercise, why not flip the switch on the stereo and get your body moving to music? That's what I tend to do. Even 10 or 15 minutes of movement is better than nothing. Walk or jog around your house, do some simple exercises, dance like a fool, lol.
Whatever you do, try and find something that works for you that you feel like you can start to adapt into your life. Set some goals for yourself and strive for them but don't beat yourself up if you fall short sometimes. Goals are achieved in steps and if you get sidelined, just find your way back to where you were and continue on.