I always wonder how private sports candidates find sponsors?

For example, if you are participating in a regional weight lifting competition, one would want to find a a sponsor as the building of body for such competitions are extremely costly and often not supported by local sports clubs or state governments. In such cases, how would one approach people for sponsorships?

What narrow segments of the people should we concentrate on? The best I could get in my country here is local gym owners who will permit us to work out for free in exchange of being a trainer in the gym for a few hours.