A friend asked me over dinner how she should start tracking her cycle, and I opened my mouth to answer and realised I was about to overwhelm her. So I stopped. Here is the only thing you have to do to start — and it fits in one sentence.

Your body has been drawing a temperature map every single month. Low phase, thermal shift, sustained luteal high, pre-menstrual descent — month after month, whether anyone was looking or not. October is the best time to start looking.