Avoid making resolutions that sound like "I will lose weight." Sometimes, the way we phrase certain tasks influences whether these tasks will get accomplished or not. "Lose weight" sounds dreary, and sounds like it involves pain or being deprived. I always thought "Weight Watchers" wasn't a great name for a business because the name has built-in dreariness. Saying, "I will lose weight," doesn't really describe how you're going to do it, either.
The subconscious hears the things we say to ourselves and leads the body accordingly.
Make resolutions that are phrased better. It's like asking the right question. Ask the right question--the one that will give a better answer. Don't ask "how much do you bench press?" ask "how do you bench press and how does it make your chest muscles feel while you do it?"
Instead of "I will lose weight," say "I will learn how to do basic weight training moves." By starting with low weights and gradually increasing them, while learning correct lifting form and eating 6-7 meals a day (adding snacks between meals)."
By February--probably before the end of January--you'll notice the changes to your body as a side effect that you get for pursuing your hobby, learning weight training moves and eating throughout the day. The positive changes to mood, energy level, even outlook on life, will also be side effects. And all this just for picking up a new hobby.