Put a little more effort into the way you groom and dress yourself. Increase your level of fitness if that is what makes you feel unattractive. Upgrade your level of self confidence if you are unwilling or unable to improve your appearance.
Practice smiling. Practice charisma and conversation. Read more, tell stories and anecdotes to yourself when you're alone, get used to telling stories and jokes. Learn to be interested in people, learn to ask them about themselves, learn to flatter.
A lot of these things feel like things you shouldn't practice. It feels like these are things that should be innate, eg "you've got it, or you don't." But that's nonsense. Anything that can and will improve your life is worth actively working on. That goes for professional or personal goals.
Perspective is the final one. Bad things happen in life. Good things happen too. Evolution has taught us to focus and fixate on negatives. Work against that. Don't tell the story of the asshole on the bus who pissed you off, tell the story of the cute kid on the bus who made you smile. Talk about positive, happy things and you'll appear to be a positive, happy person. And before long you'll trick yourself into being a positive and happy person that people would like to be around.