I've seen this before. One of my classmates went to the gym with me on a whim, and it made me sick after pushing the barbell a few times. There may be the following reasons.

First, there is no warm-up exercise, the body has not warmed up and weighed, and it can't adapt for a while.

Second, as the first floor said, there is something wrong with the breathing rhythm, and the body lacks oxygen.

Third, there is another possibility that you have a poor foundation or haven't exercised for a while, and the intensity is a bit high for you now.

It is suggested to warm up before exercise, appropriately reduce the intensity of exercise, maintain a more comfortable state, and then gradually increase the intensity.