I know it's shallow, but the first thing is losing weight. That gives you more confidence and attracts more people (including yourself to yourself). I'm on a gluten-free, high fiber diet now for my intestinal issues and weight gain. It's so hard to do, and I honestly have not lost hardly any weight yet, maybe it's the meds.
Physical exercise. Get those endorphins pumping.
Then just keep reaching out, going out, having experiences. It's like riding a bike.
You also have us here.