a mile

This masters swim course is kicking my butt. My previous delusions of being a strong swimmer have now been crushed as i'm in the slower lane while men and women much older (and seemingly in worse shape) are cruising past me without breaking a sweat. My problem seems to stem from my endurance (or lack thereof). When we do sprints, i'm good. Kicking, one armed butterfly/backstroke/crawl (or, excuse me, freestyle), etc are all good. When we get to pyramids (4 lengths, break, 8 lengths, break, 12 lengths, break, 8 lengths, break, 4 lengths, done), i fall behind. Obviously this is an area i'm working on and hope to improve upon during this course. Last night the instructions were to swim a timed mile (88 lengths in our 20yd pool). The thought was to time us at the beginning, then again at the end, and see how much we'd improved. Going into it i was sure i'd need a break, but my lane partner (who i'm faster/stronger than, but who has much more endurance than i) gave me a pep talk, telling me to swim slowly, focusing on kicks and said he'd keep track of laps (since i lose count after 4). It worked! I managed to swim the entire thing with just a quick drink of water. My time wasn't great (39 mins), but that just leaves tons of room for improvement next time!