How do you keep your longest held relationships alive?

I am genuinely terrible at friendship maintenance and so are my oldest friends. I think mostly I just lucked out meeting them and making the connections that I did because we will go years without talking and then as soon as we see each other it is like no time has passed. I guess it’s just a mutual understanding that the lack of contact isn’t personal it’s just situational and that there is enough of a foundation to make up for it.