Welcome to the team! I'm glad you like the idea. I've found that when we try to be perfect it usually ends up in feeling overwhelmed and makes it easier to give up. Instead, by going slowly and changing things over time we have a better chance of creating the healthy lifestyle we need.
I've also had issues with feeling negative, but by supporting others and believing in them it has become easier to think positively and believe that difficult goals can be reached. It's also important to start replacing negative thoughts with positive thoughts whenever they pop up. It might feel fake at first, but over time you'll find that it is a huge help.
Definitely nothing is out of reach, as long as you're willing to keep trying. Forgive yesterday, hope for tomorrow, do better today!