Aficionado

A person who is very knowledgeable and enthusiastic about an activity, subject, or pastime. You could say I am an AFICIONADO when it comes to sport and the gym. I love them! Almost addicted - in a good way obviously. Albert Einstein was an AFICIONADO when it came to science and the infamous e=mc^2. In a way, we are all AFICIONADO'S in one way or another, it just depends on the subject, pastime and/or activity.