I'd say that everyone will have some limitations of varying degrees, and mental illness too can cause great limitations but it's about trying to push past the barriers of these limitations a little (bit by bit?) for some it may be a massive achievement to just get up in the morning or go out. But with real drive and determination some people can overcome amazing difficulties (climbing mountains to weightlifting to getting up in the morning!). Maybe keep on pushing those boundaries or barriers a little more and who knows where it might lead to- that's where Scott is a massive inspiration.
Do understand how some people find it difficult or impossible though due to particular circumstances though and this doesn't make them less of a person than many others.