https://medium.com/illumination/the-greatest-debt-you-will-ever-owe-and-how-to-begin-to-repay-it-in-life-6e2308cabd84?source=friends_link&sk=22d79041b0597ae34f47f789cbbaa203
Showing gratitude and helping others are the best possible ways to pay your debt. You have already mentioned it in the article @Bill Abbate