Humans are not rational beings

Imagine it's Friday, you've just come home from work, school, or whatever you've just been doing. When you walk through the door, you remind yourself of some task you have to do, like a big project at work, or something you want to accomplish, like running 10 miles every weekend, or finally starting to learn guitar, or just trying out that new cake recipe you've read is so good.  In my case, just write one short blog. 

But you tell yourself, because it's barely Friday, I still have all the weekend to spare, so go ahead and watch all the parts of the sequel to the series you love so much in one evening. 

Saturday follows, and you've been lying to yourself since the morning, saying you're going to tackle the task at hand later in the day, but we all know you didn't. 

It's Sunday here, what else, you're procrastinating again and suddenly it's five o'clock in the afternoon and you still haven't done anything, and this very long weekend has slipped away from you. 

My question is, why do we keep procrastinating, even though we know it's bad for us? 

And hence the claim that humans are not rational, because if we were, we wouldn't procrastinate and sabotage ourselves. 

But procrastination isn't the only reason why I think we're irrational, why people eat too much, get drunk, smoke, take drugs, go to bed too late. 

All these actions are bad for us and harm us, but why do we do them despite being aware? Why do we consciously choose to do something, even if it harms us? 

To the question WHY? I don't know the answer, because I'm not Simon Sinek (just humor). But David Goggins, a retired Navy SEAL and ultramarathoner, gave a good answer when he was on the Joe Rogan podcast. 

"A lot of people ask me, what's my biggest fear in life? My biggest fear is, let's say this, imagine, I just died and now I'm standing in line in front of  god, I came to heaven, I was 75 years old, I weighed 136 kg, I

worked for Ecolab my whole life, where I sprayed insects, that's what I did. 

But now it's my turn and god says to me, hey, read this, and I start reading and I'm reading 82 kg, a member of the NAVY Seals, a motivational speaker, a record for the most pull-ups, etc... And I say to myself, wait, that's not me, and God says, this is what you were supposed to be. 

My biggest fear is that I won't reach my potential. 

I want that person up there to say: I knew you could do this. I want to go up there and leave nothing on the table down here." 

We should be afraid of what will happen if we get old and don't achieve what we wanted in life, for what exactly? One crappy series? "One" extra hours of mindles scrolling through social media? One cigarette? Why?