You either know about the luteal phase, or you don't

I stumbled upon the term luteal phase in an article at the age of 37. 
I've had a "cycle" for 20 years but I knew very little about it and had never heard that term before. What the hell did we learn in sex education again? Whose driving this godforsaken ship anyway?
Oh ya. 
Men.

The luteal phase is interesting because when you exercise during it you burn 3x more calories (what I would have given to know that all my life)

Anyway, the luteal phase is much more than that. If you ever struggled to get pregnant and visited a specialist, you may have learned about how the luteal phase affects your fertility, depending on how long or short it is. I don't know much about that either. 

What I do know is that in the 1930s, a scientist was able to determine what phase of her cycle a woman was in based on her behaviour alone, 100 % of the time. How valuable a resource is that? (1939 Study)
The reason for the drop in mood during the luteal phase is withdrawal, due to the lowering hormones. Below is a little diagram of the phases, the moods, and the hormone dips. 

I found this photo here

Anyway, the point is that there are endless things to learn about our cycles. I have a note on my phone where I add information every month, if I feel an extreme mood. I check what cycle day I'm on
(Eve app) then put in the day like this. 

DAY 24 - Crying at commercials
Day 21 - Lost my temper for no reason
Day 10 - HAPPY for no reason

It's been a really interesting gauge. And when I'm confused, down, anxious, and I notice it's the luteal phase, I'm a little easier on myself.