It's always worth it to even try. When you feel sick or unhappy, it is quite difficult to have a good attitude. Everyone has the ability to be positive under almost any circumstance. It is the key to success in any problem-solving or major lifestyle change. I don't think I've ever heard of one really successful person that had a poor attitude about everything in life.
Chances are, they see the positive in people, situations and opportunities and take action.
I hope everyone will think about their own attitude and think about ways it can be improved to be more positive. I know for myself I always try to keep in tune with my attitude and how it effects my daily life. Improving your attitude can restore your perspective on many things and help you maintain a more balanced outlook on life.