A weak mind guarantees a weak body, but a weak body does not guarantee a weak mind.
Three years ago I was commuting in bumper-to-bumper traffic when I saw a duck in the grass and felt jealous of its freedom. Yesterday my office was a cafe near the Sydney Opera House. Today I went off-roading in "the Australian bush", visited the largest deep space radio telescope in the southern hemisphere, and walked among wild kangaroos. Think outside the box. Release preconceived notions of reality. The heart can only stretch if the mind is willing to let go.
Physical training is as much a conditioning of the human body as it is the human mind. To make something a reality, we must first be able to envision it with our mind. By conditioning the mind we can push our bodies beyond our perceived limitations. You can do it -- don't let anyone, including your mind, tell you otherwise.