Food and water are two things 28-year-old Lu Mengjia's tries to avoid while working as a volunteer at the Bird's Nest.

"I try and stay away from the two because having to go to the toilet is a chore," Lu said.

She suffers from a muscle weakness and is wheelchair-bound.

"I cannot get up by myself and it is difficult to raise my arms," Lu said.

She wears a steel plate to support her back so that she can sit up.

Although thirsty from answering questions at the information booth and sweaty because of the steel support, she will not allow herself to have a drink.

Five-hour shifts giving directions to confused tourists and distributing pamphlets may not be considered leisure, but Lu enjoys it.

"In my 20 years at school I received much help and now it is time for me to pay back," she said.

Lu completed her degree in finance at Renmin University last year.

She applied to be a volunteer at the Olympics and Paralympics because she is a big sports fan.

She said she agrees with the saying of Pierre de Coubertin, founder of the modern Olympics, that "the most important thing in the Olympic Games is not to win but to take part, just as the most important thing in life is not the triumph but the struggle. The essential thing is not to have conquered but to have fought well".

"I just try my best to do my part," she said.

Although I am disabled, I can still make a contribution to society," she said.

Her sunny smile, fluent English and confidence impress many people.

"She never gets depressed and is always optimistic," Lu Ge, her father, said.

"She is the sunshine in our family," he said.

Lu is one of three wheelchair volunteers at the National Stadium.

There are 12 others helping out at the Olympic Green, and there are 10 blind masseurs working at the Paralympic Village.

They comprise just a small percentage of the 44,000 volunteers helping out during the Games, but they are all playing their part in helping others.