Holding a pose for 15 minutes, that really is impressive. If you can keep doing that you will be able to make a living off modelling (given a large enough artist community) Finding a good model is a pain. I know, I’ve sketched and modeled on occasion when no other model was available on the time we (5 artists) got together. Once a good model is found, everyone will want to work with them.
It is so great you left feeling better about yourself. But some artists do complain about a model…If you are going to do this for other artists, do keep in mind, if one of them goes “Your feet are too BIG” what they really mean is “I can’t get these damned lines right! Now I’ve drawn your feet too small”