Something I often see, in myself and others, is a tendency to transform into slightly different people when we exercise. For instance, a client and I will be chatting comfortably, but when they go to show me an exercise they may turn into some version of the Incredible Hulk: jaw set, arms braced, breath quickening as they push themselves into position.
I think there can be a great joy to taking on a persona when you move. It can feel like an escape, or as if you're homing in on and sharpening a particular aspect of yourself. You may not even realize you're doing this, it's become so second nature.
You just want to check in with who you are becoming. The Incredible Hulk is kinda stressy; he was not a happy camper. The movement we're practicing in the gym needs to help us move better all the time---at the very least, it needs to not make us worse---so, unless you're a power lifter, most if not all of the moves you're doing should look and feel as calm and relaxed as the ones you do the rest of our day. Dancers, martial artists, and more learn how to build up incredible strength and stamina using calm and ease. I think of Bruce Lee's commandment to "be like water". It can be done. It will take more time. But it will help you become a much healthier and more effective mover.
Besides, "for he who is calm, the whole world falls at his feet"---I could swear I read that somewhere.
Hasty or ragged breathing, aggressively moving yourself into a position, and overriding your body's pain signals---these things can increase the body's sense of threat, which can tell the body to send warning signals in the form of pain, tension, bracing, and even possibly inflammation. Moving into things slowly and gently with calm, easy breathing can help the body feel safe. Feeling safe helps reduce the body's sense of threat, and reducing the sense of threat helps the body heal. So you are most likely to maximize your chances of reducing injury and improving health and performance when you practice calm, relaxed, and fluid movement.
This is one reason why you may have to "regress to progress"---you may not be able to do what you want to do yet, but like young ballet dancers, eventually you'll be able to fly across the floor. It's also why, when I suggest exercises, I encourage people to do them with the same ease, breath and attention with which they would sip a favorite beverage or read a favorite book. It can be truly amazing to watch and feel this transition in yourself. Again, it can take time and patience. But it can often be invaluable to preventing injury and----what do the kids say these days? oh yes---optimizing movement potential.