Stretching the limits

I learned a very valuable lesson today in the pool, but that was after a run in the snow and ice.  The pool session was based on breathing.  We started by swimming 200m but every 25m we changed the frequency of breathing from 3/5/7/5 strokes which took up 100m and then repeated - then you had a 15 sec break before repeating the set twice.  Normally I'd breath every 3 strokes but when I get tired it drops to every 2.  5 was a push and 7 almost impossible.
We repeated the exercise on 6 x 100m and again I struggled with 7 and sometimes with 5.  And again on 8 x 50m and except this time it was breathing only every 5 or 7 strokes - I managed it.  The final set was 6 x 25 but the breathing changed to every 7 & 9 - yes 9 strokes.  Guess what?  I managed it.  To top things off I then swan 25 m without taking a breath which for me was incredible, especially when I repeated it.  In total I swam 3,000m which isn't bad considering I had run before it.
So the moral of the story is with an incremental plan you can achieve greater results.