✉ Envelope #48: Three life-changing concepts I came across recently

Happy Friday! Andy from Back of the Envelope here.

Today I want to share three things that have had a huge impact on my life recently.

Each one carries its own weight. But when you hold them together, something shifts.

The first two apply to just about everyone. The last one will hit different if you're a parent.

I could go deep on each one, but since we’ve only got a few minutes, I’m going to keep it tight. Let me know if any of these resonates and I’ll happily dive deeper in a future email.

Let’s go!
(Estimated read time: 3 minutes 0 seconds)

1. The 90-Second Emotional Response

Ok, I’m going to be openly vulnerable for a second here...

I’ve struggled with managing anger and frustration.

Not usually with work or engineering-related things. But with life stuff… and parenting.

If you know me in real life, you’ve probably never seen this side of me, because most things just don’t get to me.

But every now and then, something cuts through — and when it does, it really messes with my mind.

I’ve tried the usual stuff: meditation, breathing, relaxation techniques. Some helped, but it never quite clicked.

Until recently, when I was listening to an audiobook called The Let Them Theory by Mel Robbins (highly recommend, by the way), I stumbled across the "90-second emotional response rule."

The concept comes from Dr. Jill Bolte Taylor, a neuroanatomist:

That stopped me in my tracks.

What this means is that when something really pisses me off, my brain floods my body with adrenaline, cortisol — all that fight-or-flight stuff.

But it only does it for roughly 90 seconds.

After that... it’s on me. I can either keep replaying the story that triggered me, or I can let the storm pass and shift.

Which explains why the whole "just breathe" advice doesn’t seem to work when we’re in the heat of the moment. Because the chemicals haven’t dissipated yet.

So now, when something triggers me, I wait.

I count 90 seconds.

Then I choose.

And that leads into the second concept.

2. We Only Have About 4,000 Weeks to Live

The average life expectancy in the U.S. is about 77 years.

77 x 52 = 4,004 weeks.

If you’re like me, you’ve probably already gone through half of those.

I made a spreadsheet to visualize it.

Each dot = 1 week. Each row = 1 year. The blank dots? That’s what’s left.

Seeing time like this… it changes things.

It reminds me how short life is. It helps me catch myself before I spiral.

Why stay pissed over something small when I only get this many weeks total?

The 90-second rule becomes easier to practice when I know how precious each moment is.

And that brings me to the third concept.

3. By the Time Your Child Turns 18, You’ve Spent ~90% of the Time You’ll Ever Spend with Them

Let that sink in for a second.

Back of the envelope math:

• First 18 years: spend every day with them = 18 * 365 = 6,570 days

• After 18: maybe I see them every other week for 30 years = 52/2 * 30 = 780 days

• Total: 6,570 + 780 = 7,350 days

• Time spent by 18: 6,570 / 7,350 = 89.4%

Nearly all the in-person time I’ll ever have with my kids... happens before they’re 18.

I added this onto the same chart from earlier. A little rectangle showing how much time I’ve got left until all of them turn 18.

…Every dot matters.

To bring it all together:

• When something or someone pushes our buttons, remember the 90-second rule. Let the chemicals run their course. Then choose our response.

• Zoom out. Life is short… especially when measured in weeks. Most of the little stressful events won’t matter in a month, let alone a year.

• And if it’s our kids testing our limits... remember how little time we actually get with them. That perspective alone is rewiring everything for me.

Thanks for reading!

Andy Lin
Back of the Envelope/Structural Engineer HQ

PS.

Speaking of time — if you want to spend less of it stressing over moment frame connection design and the chaos it can bring during construction, check out DuraFuse Frames.

It’s a code-approved moment frame connection.

And they’ve got your back with full design team support: connection calcs, plan check comments, RFI responses, shop drawing reviews — the whole shebang.

Here’s that link again: https://go.sehq.co/durafuse

PPS.

I remember dropping off my son on his first day of school. He looked worried, so I asked, “What’s wrong?”

He said, "How long do I have to go to school for?"

I smiled and said, “Until you’re 18."

He paused, nodded quietly, then asked: "You’ll remember to come get me when I’m 18, right?"

(not a true story)