noun
mileage run; travel hacking
Colloquial term for deliberately taking flights or using credit cards to accumulate frequent flyer miles, often with a humorous or self-deprecating tone.
週末に沖縄までマイル修行に行ってきた。
I went on a mileage run to Okinawa over the weekend.
彼はマイル修行のためにクレジットカードを何枚も作っている。
He has opened several credit cards just for travel hacking.