Our greatness lies not so much in being able to remake the world as in being able to remake ourselves.MAHATMA GANDHI
To be great and feel great is to be true to yourself. Finding your values, your passion in life and start living according to this. Do not try to change others, (chances are very small you will succeed anyway :-)) but change yourself.
When you find your values and practice them consistently, and follow your heart as well as your head you will see amazing things happen! When you feel great you will BE great. But you need to do this long-term, and have the self-discipline to get the results.
I wish you all the best. Be Great.
Take Care. Namaste.