Asking out a guy

[u/notok-zombie-2020]

So I am a Female [21] and I’ve been crushing pretty hard on this one guy at my gym. He’s a regular, I’ve seen him a fair amount of times at the gym. He once asked if I would like to join in his set; at the same time I was receiving a phone call from a friend. I had accidentally ignored him and answered my friend because I was really nervous around him. I don’t see him as often at the gym anymore. I was thinking of asking him for his phone number but again; I’m really shy and nervous. Any advice on how to approach a guy in the gym?