Every decision to succeed at something is a decision to fail at something else.
It's not about commitment; it's about budgeting. There's no slack. I don't spend any time on the couch*. With fixed reserves of time, energy, money, and will, all of which are already allocated, choosing to get better at something must come with a cost.
And there's a beat-the-bomb mechanic: because of the presence of the overhang, plus the risk of dispiriting yourself and giving up, if you commit to too many things, you don't get an arbitrary subset of them - you get nothing.
With that in mind, I present a New Year's planning tool that I call the Anti-Resolution. An Anti-Resolution says "This is something I care about, and would like to commit resources to, but I'm not going to. I may go after it opportunistically, but it will always lose against my other goals. I have thought about, and accepted, the consequences of this".
Accepting the consequences in advance is key; it'll stop you second-guessing yourself. This prevents distraction. Plus, at the end of the year, instead of tearing yourself up for not doing X, you'll be able to look at your logs and say "I deliberately chose not to achieve X, because I decided that Y was more important". (Of course, if you also failed at Y, you have a problem).
For example: Buying a house is an Anti-Resolution for me this year. It's something I dearly want to do, but there are other things that are more important. Similarly, I'd love to get really good at climbing, but I don't dare split the resources that are needed for swing dancing.
I think that a list of Resolutions without an accompanying list of Anti-Resolutions runs the risk of being unrealistic. What are you prepared to give up, in order to achieve your goals?
The other new tool in my 2019 planning is the Kill Clause. If a Resolution has a Kill Clause, it means that, if you fail at it this year, you will never† attempt it again. The goal is to prevent repeated identical failures, for two reasons: one is that failures waste resources, and the other is that failures beget failures. Your identity is what you have proved to yourself; you don't want to accidentally prove to yourself that your goals mean nothing.
The Kill Clause is designed to protect, not punish. The idea is that, if you've failed at X, you've demonstrated that you can't - or shouldn't, or don't really want to - do it. It's perfectly valid to learn that, as it turns out, X doesn't work for you.
Or, as W C Fields put it, "If at first you don't succeed, try again. Then quit. No use being a damn fool about it."
*: Actually I do, but when I'm on the couch, it's because I'm too exhausted to do anything else. I haven't run out of time, but I've run out of energy.
The cheat, of course, is to plan and execute projects that permanently increase your capabilities. As any board gamer knows, over the long run you're always better off spending resources on things that'll generate more resources, at least until the endgame.
†: Well, not for a while, and not in the same way. These are tools, not dogma.