I am wondering if you meant that gym members are approaching you for free advice. It is not wrong for you to turn down requests for free advice. I would often answer one simple question from a gym member when I was working for a gym. But if there was a second question, I would say “we should set up a time for you and I to have a training session so I can give you my full attention and you can ask all the questions you want”. This would either result in a new client or they would admit to just wanting free advice in some way. If a gym member tells you “I just want a couple of questins answered”, it really means they want your knowledge for free. You will have to decide where to draw the line.