My gf wants to go to the gym with me and I really don't like going to the gym with people.

It's my "zen time" so, I like to work out alone. I also like to hike alone. I like to spend at least 3 - 4 hours at the gym or hiking and whenever go with other people they never want to stay that long, and end up leaving early because they want to leave. So, lol that's pretty much why I don't want her to go with me because I like to work out on my own time. I told her that I wanted to go alone and she got really sad and keeps trying to go with me still and I really don't want to go with her. LOL I feel like a butthole but, whatever.