Is it weird that I'm too nervous to work out with the guy I'm dating?

You just said “he’s a very mellow, non-competitive sort” and that in in itself describes the perfect workout partner. I think you should cast aside your nervousness and take him up on working out together and what better way to spend time together and to get to know that side of him! I bet you will be glad you did!

You need to be honest with him that you are uncomfortable exercising in front of him .

What @marinelife said, except tell him it is in front of any friend or partner, that you get self-conscious when someone you know is with you while you work out. That way he won’t feel it’s about him..

This is common. There are gyms built around this psychology. Some gyms try to make it possible for everyone to be comfortable. Some are women only. They have other tricks.

Still others take the opposite approach. It’s all about competition and being seen. They want to have the hottest people working out there. That’s why they put all the exercise machines in the window—so you can see how buff the people are who use that gym.

In the end, I agree with @marinelife and @zenvelo. You have to tell him the truth. If he accepts it, great! If not, then yes you are out a relationship, but it wasn’t a relationship worth keeping, anyway. Just hope he really isn’t competitive, and he really isn’t judging you by your physical fitness. But if he is, then he was never the right guy for you. Better to find out now then later after you’ve sunk a lot more time into it. And make no mistake—this is not something you can hide. He’ll find out eventually. If you think this has long term potential, tell him now. Of course, if this is just for a few laughs, then there’s no need to tell him. String him along until you’ve had your fill.

It is not weird at all. It is simply a personal choice. Some people like the motivation that a workot buddy or group environment creates. Some people prefer to focus by themselves.
As @wundayatta stated, you need to simply tell him what you prefer. He should accept this and not keep asking you to change what you like. Your preference is your preference and it should be respected.
Good luck.

Not weird. People get weird about all sorts of things with new people they are dating. Eating in front of them, working out with them, when they can hear them going to the bathroom, so many things.

Some people above are saying it is your personal choice to work out alone, but it does not really sound like that is the real explanation. Maybe I am wrong. It sounds to me like you compare yourself a lot to others, and might be fairly insecure, and worry a lot about being embarrassed. Feel free to correct me if I am wrong.

If I am right, then with your boyfriend, if you both are fairly serious, I think you should take him up on his offer a few times.

Get over it. Take him at his word. He won’t care if you sweat or huff and puff; that is what gyms are for.

Sounds like this is molehill being expanded into a mountain. No reason to be worried.

If this guy is really interested in you, he expects this from you and it should not be a problem. You should have seen me running a one-mile circle track for the first time in 14 years. I embarrassed myself, but I did not give up and I had a lot of support. I was 58 years old.

When you love someone, you love the good and the not so bad parts, too.

Talk to him and explain how you feel about running with him. He will understand.

After all, he himself was in your position at one time or another.

It sounds like you are in reasonable shape yourself. I would take control and suggest a run you are comfortable with and set the pace. It isn’t a race and it shouldn’t be competitive. If he isn’t happy with that then he has a problem.

Just tell him you prefer to work out alone. He should respect your preference. There are other activities you can share.

My soul mate and I work out ‘together’ on occasion, but her focus is different than mine. While I go out of my way to give her an occasional kiss or touch, she does her thing and I do mine. We do usually start out walking on the treadmill together, but even still, what she is doing is kind of not my business, and vice versa. Even if we were trying to attain similar goals, it is nice to have the freedom to pursue them in our own ways.

Perhaps the way we work out is somewhat indicative of many facets of our relationship.