The really fit people don't care what level you are on the treadmill , they are too much in their zone to even notice . The almost really fit too , unless you're me, who is trying to work out what to make for dinner, whether all the bills have been paid , and trying to remember when the animals were last wormed . That and bitterly resenting the fact that I'm having to work twice as hard as my younger colleagues to maintain the same level of fitness.
I had a serious accident, that meant I put a lot of weight on, and left my fitness levels on the floor . Id never been to a gym in my life , I'd only ever run outside, and I used to do that in the dark. Still do , even though I am fitter now than I was before the accident. But I gritted my teeth, and yes ,at first I was the slowest person there . But not for long . You get faster , in a fairly short time . Other new people join, who have to start from the beginning . And one day, OP, you become the person the new starters are looking at , thinking " I'm never going to be that fit " . Really . There is always going to be someone fitter than you , but there will also be someone slower .
The fact that you're there at all, is the hardest stride out of the way.