As if there is someone better that you are supposed to be! You cannot turn yourself into someone else, better not waste your time trying. In any case, if you lose 10 pounds or run that marathon, if you earn that amount of money or get that promotion do you really think that the worries that keep you awake at night will cease? That your suspicions about your deep inadequacy will magically be shed like the weight, cast off with the miles run? Of course not.
There is so much joy, peace and happiness to be found in the realisation that you are already whole and good and have so much to give. It doesn't cost anything and you can start right now.
Find someone you admire, not because they are rich or beautiful, but because they seem to be happy and full of generosity, because they move through difficult times with grace, because they are authentic - use that person as your inspiration. Look beyond the surface of things to find your heroes.
Don't wait! Don't put it off until you are thinner, more financially secure, braver, have company. Don't procrastinate! Start here, where you are today, start talking to yourself as if you were your own best friend, start being kinder to other people, as you wish others were kinder to you, start taking the pressure off yourself, smile at the world and see if it smiles back (and when it doesn't, don't let it get you down, learning how to bear that is called resilience). Stick with it! What you are embarking upon is a way of living, an internal transformation, an experiment in kindness and acceptance directed both inwards to yourself and outwards to a world which is sorely in need of it. And as you move forward in this way, you will surely begin to notice how all the other facets of your life simply fall into place, either because they are the natural outcome of the way you are living, or because the new way you are living helps you to sort that which is necessary from that which is only background noise.
It's not easy, this continual turning back towards what truly matters - if it was easy then everybody would be doing it and they quite clearly are not. You will be ranging yourself against the power of global advertising to make you feel inadequate, you will oftentimes find yourself turning away from the group, as you prioritise your health and well-being over group dynamics. But deep down, you know what is important and in small increments you can create a life dedicated to seeking and abiding with those things. You will feel the benefit, no doubt, but more important than that, so will everyone else around you: energised and happy people give more, have more time for others, are kinder and more patient. So what works for you will work for everyone else too.