Updated: Dec 28, 2021
Because you are either born with it, or you're not. Yes there are degrees of resilience. However generally speaking, you have a lot or not much and there's nothing you can do to get it. So forget about it.
If you have a lot - lucky you.
If you don't, you will need more support structures around you to succeed.
Example. Some people can get out of bed at 5am and jog every day.
It gets tedious for them, but they're resilient and keep doing it.
If you can't keep doing it, you are not resilient and need structures around you to continue. E.g your sports gear and keys ready to go // a personal trainer knocking at your door // a commitment to your mate to meet at your front door at 5:05 am ...