It's a problem.
You have to buy tickets early.
Months in advance, usually.
Even then, I'm only batting about 500.
Plus, if my wife flies with me, we can't sit at the emergency exit.
She can't answer their questions about being physically capable of opening the doors in the affirmative.
southwestern goes where delta goes and they do not have the cramped seating. They do dollar you to death though. British Airways bumped me up for free without asking for it due to my size. A great airline