After 35 years, i quit smoking and started vaping almost a year ago
For me, after 3 to 4 weeks i started to notice i was getting up the hill from my place with much more ease and less breathlessness, and its only gotten better from there.
I can honesty say that its like i have my lungs back, and as ive said on here before i no longer fear lung volume tests at my GP check ups.
Vaping wont suddenly undo all the bad effects of smoking or general ill health though, despite smoking i have always been very active, long walks/treks etc.....now i just do them easier.
As above, apart from rare sensitivities to VG/PG or flavouring, overindulgence would be your only possible way to feel breathless. Im not a cloud chaser, i dont see the point of trying to cram any more vapor into my lungs than smoke when i used to smoke....to add to that i use temperature controlled mods and do not do bonkers watts, as i further believe its completely irrational to want to cram overly warm to downright hot vapor into sometimes decades long damaged lungs.... (ill wait for the usual flaming from the watts/cloud chasers)