How are your lungs?

Breathing on both sides during front crawl, e.g. every 3 strokes - you're exercising much more control over your breathing / slowing it down.

Since doing swimming lessons when I was like 10, I've done this, but recently I like to try to push it by doing 5 or, if I can, 7 strokes in between breaths. I honestly think this has had an impact on my lung capacity. I have no science to back me up, but I just feel like I can breathe deeper and easier than I used to.