Her attitude helps me to change mine. She doesn't need to try to impress me and she knows it. She tried the switchback because she wanted to clean it. She holds herself back on the downhill because she rides where she feels safe. I usually push myself until I crash. I find what my limits are and she sets hers. She gets faster because she allows herself to. I get faster because I force myself to. She grows exponentially every time she rides. I wash out on a wet rock and it takes me a while to recover because I have to heal and overcome the mental block that was placed when I went down.
Try riding with a beginner. It's a different kind of fun. You'll need to adjust how you look at the ride. You may even need to adjust the course you ride. The person you're riding with will appreciate it. And if you're riding with your girlfriend/boyfriend/spouse, you may stay together after the first ride. Just make sure not to push them too hard, so they enjoy it. They'll see why they would want to be pushed or even push themselves. Some of us forget that. We grew up knowing how to ride a bike the way we do and don't remember when a rock garden could have looked like anything except a good time. The trail that you think is beginner friendly could be notably more technical than you perceive it. So get out and ride with someone new, but be prepared to adjust your agenda.