I've felt it before in a swim. After struggling in the water suddenly it's like entering this 'zone' where you're just gliding through water. I was struggling the past few swimming sessions because I was so determined to 'correct' my swimming form to no avail, and today after struggling for the first 2 100m, I just, glided. Everything worked in unison; my strokes, my bodyroll, my balance were in sync and I stopped caring about my overturn and anything else. I just swam. And swam. It felt wonderful... like falling in love. hahahah it's true!
I was so psyched that I continued till I did 1km.
10x100m of bilateral 5 strokes each.