I am not a donor on my license yet because I am unaware if I can even donate due to my Cystic Fibrosis. Once I can get that cleared up there is no reason not to. It is undeniable that in the future I will most likely need a lung transplant.
I know many people who have been given the gift of life again through organ donation. They got to kiss their husband/ wife again, hold their children again, and laugh again. On the other hand, I know many though who waited in the list for months and months only to pass away due to lack of donors. People who could have potentially lived if others had simply talked to their loved ones about their wishes.
People may choose to be donors, but if they don't express it to those who would have to make that decision for them it might not happen. Your family is already greiving, and having a stranger ask for your body parts and having to make a split second decision doesn't usually end up with a donation. Please let your wishes be known.
The 8 life saving organs such a lungs, liver, heart, etc. can only be donated if the individual dies of "brain death" or trauma to the head. Tissues, muscles and skin can be donated otherwise and are equally important.
It only takes a few MINUTES to decide but can give someone many YEARS of life that they might not have had. According many donor associations, most major religions support organ donation or say the choice if up to you. Giving life is the ultimate gift, and I urge everyone to donate.