Free will is one of those topics where extraordinary claims should require extraordinary evidence. If there's one thing that each of experiences every day, it's the experience of thinking about stuff and making decisions. The fact that you considered the topic and decided that "free will" might be illusory is itself a data point in favor of free will. I know that I personally decide things all the time. When you have a lifetime of first-hand experience with reality, it should take gigantic amounts of extremely high-quality evidence to even budge that prior. Your reluctance to adjust your prior should only go up once you get into it and realize how much of this debate is just a semantic argument about what the term "free will" means.
You’ve never wanted to change something- maybe even something really important and failed repeatedly? Think of all the people wanting to lose weight, learn a new instrument, stop drinking, save money, etc. Also, the idea of where do our thoughts come from? Some of the most meaningful things I’ve ever done have been almost without any thought at all, they just happened or I just knew it what’s I would do. I often find the more I have to think about something, the less likely it is to happen. Why did I become a teacher? No idea just knew it was what I wanted to do and I love it. I was confident who I was going to marry pretty much 8 years before we ever even went on a date. When I cleaned up my health, it just happened. I went on a treadmill one morning, threw away all my weed, started eating less and just kept doing it. There was no plan or forethought.
Our preferences are complicated. When I see a hot chick, I definitely notice that she's hot. My upper brain knows that I'm married and I have no interest in "stepping out." It also knows that lust isn't the healthiest emotion to marinate in. But my lizard brain still knows that hot chicks are hot and pleasant to look at.
Likewise, my upper brain knows that it's a bad idea to eat a pack of Skittles every day. They have no nutritional value and are just empty calories that will do nothing but make me squishy. But I can't hide those Skittles from my lizard brain, which knows that they taste good and will conjure up evolutionary memories of finding some desperately-needed fruit in the savannah or something.
The researcher promised me ten bucks if I could sit here quietly and leave that marshmallow alone. Ten dollars can buy lots of marshmallows, so obviously I should take that deal. But that marshmallow looks pretty delicious, and it's awfully tempting to eat it right now.
When I'm driving, I'll often put my "driving brain" on autopilot and let my internal monologue keep me entertained. Then 80 miles fly by and I suddenly realize that I don't really remember any of the highway I just covered, because I was zoned out.
None of these things really disturb the notion of free will. Right now, I'm voluntarily choosing to respond to your post. I didn't have to do this. I skipped over a bunch of posts that, in my judgement, were written for the purpose of starting a dust-up, and that was an intentional decision on my part as well. I've gone through weight-loss phases similar to what you describe, and they were all motivated by a realization that I was getting a little heavier than I'd like, so I made some dietary adjustments.
Obviously some of this is thermostatic -- we don't freely choose to breathe, or freely choose to regulate our blood pressure. Probably people naturally eat a little less when they're getting fat and eat a little more when they're getting thin, although it should be obvious just from looking around that people can choose to override those nudges if they want. But all this stuff really means is that our preferences are more complex and opaque than what we might realize. Not that we don't have preferences and act on them.