I'm not a big believer in resolutions, but I love dreams. I prefer you let your imagination go, and take the hint it offers up.
I say, be brutally honest with yourself, without the brutality part. Then, make a choice.
If you don't know why you want to exercise more, and why you haven't been making the care and keeping of your body a priority, will "resolving" to go to the gym help? Ask any gym owner; most people show up for a few weeks, then keep paying for a membership they never use. Because they're only doing it to keep a cardboard promise.
Wouldn't it be better to discover a physical activity you truly love, with a community that notices when you show up and push yourself? Fencing, trail running, or cycling with a club? What do you secretly wish you could try?
If you allow yourself the thrill of discovery, the need to force and cajole takes a back seat to jumping into your special clothes and getting sweaty. You show up because your friends (often new) are expecting you. The swagger of being a person who challenges your body takes over, at least for a short while.
If I can wish for one thing for you this turning of the year, it's to allow yourself to discover the activities that make you better, more yourself, and as a sideline, fit. Of course, any commitment takes effort, and the best ones require sacrifice. I'm betting you can handle it.
What do you know, deep inside, is crucial for your happiness?
Let that be the goal that guides you, on January 1 and every day after.
Happy New Year