This is my friend Beth, an adult (about my age) who has Spina Bifida. She uses a wheelchair full time. She volunteers for CASA, where she is an "advocate for the safety and well-being of children who have been removed from their homes due to parental abuse and neglect." She is also awesome at the sport of rowing, has won silver and gold medals and is working toward the paraolympics. She is very involved in her local YMCA as she trains for rowing and is helping to raise money for a kids camp there by public speaking in the community.
If you're interested in watching an adult who has SB live a full and active life, take a look at this:
And here she is, ROCK CLIMBING! She can climb 8 feet now, and she averages an extra foot every time she tries.
Doesn't look like such a bad life, does it?