So I've been going to planet fitness with my friend the past month so we can workout together. I haven't been to this exact location for a while and some of the people I knew left and new people work there now. There is this really cute girl that works there and caught my eye. I say the usual hi how are you type deal to her but there isn't any content in the conversation. I've been trying to figure out how to get past the opener and ask for her number but I can't seem to find a way how to. I am usually pretty good with openers and creating a conversation and so forth but I just find it troublesome to pick up a girl who works at a gym. I have caught her numerous amount of times looking at me and one day I didn't workout with my friend, and my friend told me she asked where I was that day. So I guess my question for you guys is how can I approach this girl and ask for her number?

One I used before was to ask her if she is a personal trainer. Ask her if she teaches any classes. I'm not sure of Planet fitness works, but most my gyms offer classes and most people who work do some type of training.

Or you could simply ask her if the gym offeres x,y,z.

Me: Hey does this this gym offer a spin class? I just signed up for a bike race/marathon.

Her: Yes we offer blah blah

You: That sounds great, hey what about you, do you bike/whatever? I need some tips. Or even, you appear to be in good shape do you do x,y,z?

At the very least you start a convo, and you aren't hitting on her your simply asking for advice.

YOUR WELCOME FOR THE TIP BRO!

Thanks man I'll be sure to use it next time I see her

If she's looking at you and asking about you when you're not around, there's no need not to open direct. Tell her you've heard she's been asking about you and that you hope she's not a stalker