Losing weight will make you happier
Contrary to popular belief, thin doesn't equal happy. In my case, weighing less was a novel, bubbly wonderland for a while, but depression, anxiety, my suck-ass romantic situation, and my shitty job were all right there waiting for me once the spell wore off. I'm much happier today than I was when I was obese, but it's not because I lost my weight -- it's because I did (and continue to do) the inner work I needed to do so I could treat myself well consistently.
Losing weight is the hardest part
Nope. Losing weight is hard to do, for sure, but compared to the years to be lived post-weight loss, the weight-loss period is usually brief. I've had to hit my goal weight a gaggle of times, because the hardest part is continuing to make healthy, mindful choices in the millions of moments that come after the weight is lost. Because we're self-sabotaging ninjas, most of us revert back to our old habits post-weight loss, and we gain all our weight back and then some. Only those willing to do the work to get a handle on self-sabotage can expect to keep weight off for the long haul.