I think any of us can be healthy and happy, or very unhealthy and unhappy, at a surprising range of weights. Your "ideal" weight will be one that you can keep without any extreme behaviors. If you're exhausted, overtraining, and undereating to maintain a particular weight, that is not your happy weight and it's definitely not ideal. You can't expect your body or your mind to sustain a level of stress and pain indefinitely. A happy weight is actually happy. You feel good, you're not hungry all the time, not chronically sore, not living in fear of gaining weight if you make one wrong move. Maintaining your happy weight will require awareness, but not vigilance, not fear. You shouldn't be walking around feeling like you're always on the brink of disaster. You should have confidence in your ability to handle all of life's situations (vacations, injuries, illnesses, work drama, in-laws) without weight gain being a factor. In other words, your happy weight shouldn't be dependent on adhering to a strict schedule or only eating certain foods.
Much of this is related to mindset, because beliefs tend to produce certain outcomes. When I believed that could never weigh less than ___ (arbitrary number) without months of extreme dieting and grueling training, that was true for me. It wasn't true because it's such an unrealistic weight but because my approach wasn't healthy or sustainable. Months of hard training while undereating always led to binges, rebellion, and regain. My behaviors and attitude were the real problem, not anything about that particular weight. When I approached it in a totally different way--healthy habits, fun, flexibility, gradual changes--my weight easily settled in a great place. I'm working out less, enjoying my food more, and not doing anything nuts. There's no stress response to keeping this weight because there's no stress. Nothing hurts. There are no nagging injuries, no lingering fatigue, no chronic soreness. I'm well rested and I'm well fed.
My advice is to focus on health, happiness, and feeling your best first. Don't fall into the trap of judging success or self-worth by a number. If you make it all about great, enjoyable daily habits, you might be surprised how easily you maintain a lower weight, or how fantastically awesome you look and feel at a higher one.