Do I just have to be in shape to ride?

Hi there. Just a little background: I’m 30 and plus size. I’ve been up and down on a weight loss journey for the past 2 years. I’ve lost 30~35kgs at this point.

2 weeks ago I started having sex with the guy I’m seeing, and it was painful the first night. We tried a few positions and I tried to ride, but the pain was too excruciating. The next day we had missionary sex a few times and it went very well.

A week later, we meet up and I tried to ride and boy oh boy was I not prepared for how much bouncing I would have to do.

I watched videos beforehand and I learnt about the grinding back and forth/ milking technique (on my knees) as it requires less work, but he didn’t seem to enjoy that very much. He was sort of pushing my bum up and down on him. And then he just fucked me back himself eventually.

He always prioritizes my pleasure, no matter what position, but I feel selfish, I want to ride, but I don’t know if I have the stamina yet. Do I just need to keep losing weight and working on gaining strength in my thighs?