the choice of happiness

i have a BFA degree in theatre which essentially makes me an expert on nothing.
that said, it seems to me one can look into the face of another and immediately form an opinion regarding their state of happiness.
i see homeless people with next to nothing looking happier than people in expensive cars who have a job and a house.
i notice these faces, because as a cab driver, i spend 12 hours a day cruising the streets and seeing faces. i see far too many sad faces. i don't know what people are so sad about, but i can guess.
how about no health care? crappy salary? lousy benefits? bad marriage? kid problems? their dog died? the economy? the war? the price of food and everything else? thinning hair?
aging? loss? depression? this list is endless i think.
and now to happiness. i believe happiness is a choice. i see people in wheelchairs who are happier than those of us running down the street.
life gives us a variety of challenges. no problems. i don't recognize or legitimize "problems". for me, a "problem" is an opportunity to find a solution. hence i have no problems.
and happiness, at least for me, is always a choice i will make. you can choose fear, tears, anger, resentment, constipation, etc, etc...or you can choose happiness.
which will you choose?
i will choose happiness.
i may even develop a course in it, and/or offer motivational speeches on how to be happy.
and i'll be much more economically attractive than tony robbins.
peace