How to become a Marathoner?

How do you guys step up and face on the marathon distance???

Been running half marathons during trainings and races but never tried to ante up the distance out of fear. I just see it as a grueling distance na nakaka disintegrate ng katawan. Sobrang kudos talaga ako sa lahat ng mga marathoner/ultras no matter the pace or time.

Longest I’ve ran was 25km and that was physically demanding and time consuming.

How many years did you guys train to be confident enough for a marathon? Or how do you guys find the time to train for it?