After training with a Navy Seal, an entrepreneur explains why everyone should have a 'f--- it list'

How many days from last year do you remember?

Really stop and think about it.

Now see if you can identify any patterns among those days that stand out. Were they all happy? Upsetting? Relaxing?

According to Jesse Itzler, we're more likely to remember experiences that are unpleasant, at least in the moment.

Itzler is the cofounder of Marquis Jets, owner of the NBA's Atlanta Hawks, and a former rapper; he's also married to Spanx founder Sara Blakely. In 2015 he published a book, "Living With a Seal," about his month-long experience training with a Navy Seal.

Itzler recently appeared on The James Altucher Show to discuss everything he's learned about success, failure, mental toughness, and finding meaning.

In order to ensure that he's living a memorable life, Itzler told Altucher that he recently started keeping what he calls a "f--- it list," replacing the "bucket list" that he used to have. The goal of the "f--- it list" is to make a habit of doing things that are painful or uncomfortable, but help him grow.

What's on it?

"Those are things that suck, and those are things that are challenging, and those are things that require preparation, training, planning, maybe failure," he said. "But those are the things that make me feel most alive. And those are the things that teach me the most about me."

Itzler emphasized that everyone's "f--- it list" will be different, and you can start with small steps forward. On his he's included physical feats, like riding his bike cross-country in less than four months and paddling 100 miles. And since he has a hard time with new languages, he also wants to learn the national anthem from 10 different countries.

None of them will be easy, but all of them will make him feel like he's accomplished something and changed his life for the better. As the Navy Seal once told him, "If it doesn't suck, don't do it."

Itzler explained that the point of having a "f--- it list" is to be working your mental toughness "muscle." It's something he learned while training with the Navy Seal, who made him do 100 pull-ups in a row on his first day of training and swim in a frozen lake during a blizzard.

Each one of these experiences further strengthened his mental toughness muscle, he said, and allowed him to push past his limits.

"Once you change your set point, [once] you raise your baseline from wherever it is to a higher level by doing these tough challenges, getting out of your comfort zone, [and] pushing your limits, it never goes back down," Itzler said.

"And all of a sudden you start saying, 'I don't wanna take the easy way. I'm gonna take the hard way.'"