Can you not feel yourself getting out of breath, it a fairly basic rule. If you don’t have the fitness to do a job stay away from it.
You don’t have to be a genius to understand your fitness levels
It’s not "out of breath" as in panting like a you’ve just run up a hill and which you’d notice as you won’t be able to do much else. It’s elevated breathing which you don’t normally notice, for example briefly swimming against a current or getting a stressor or shock as you get caught up in some line or a shark swam past when some adrenaline kicks in.