Tips for Makeup at the Gym

I am a personal trainer and I like to wear at least a little bit of makeup when I know that I am going to be meeting with a client. Of course the problem is that I clog the pores so much when I sweat but I really need some sort of concealer on my face. Are there any free makeup tips for someone like me who really wants to wear makeup at the gym but I do not want my skin to break out after a good workout. Maybe something light and not clogging and hopefully even water proof would be great.