This past Monday I was standing outside the classroom with my peers during a short break.  I was telling them that I had a meeting after this class, before my next class at 1 pm  which would last until my last class at 4pm.  In other words, I was not going to have the one hour 12 -1 window to get in my weight training during the day.  I would have to go at the end of the day.
One of the women, who is in a different program (human development and family studies) than I (public health) said and asked, "You lift weights?"  "Why would you do that?"
 It was a serious question.  She is a young woman, in her mid to late 20s and she was raised in another country but I do not know much about the culture there.  I imagined that she asked me those questions because her country does not make as big a deal about health promotion and physical activity as some countries do, but I do not know that for sure.  I do know that she sounded genuinely surprised.

My quick list of reasons was:
to be stronger
to prevent osteoporisis
to improve balance
to increase the chance of healthy active aging

And one of my friends added:
to increase muscle mass which is more metabolically active than fat mass(well, I am not sure that is how she said it, but you get the idea - burn more calories)

This all reminds me that I do have a website which, though woefully in need of an update, has some good fitness information.  It has a section on strength training that you might find helpful.   You can visit it here.