This phrase can reflect what is normal in one's culture, which may differ internationally. In Spain, they think nothing of having dinner at 10 p.m.
Pro Tip 2/3
Subjective Normalcy
What's surprising to one person may be normal to another; this phrase highlights such differences. She thinks nothing of running marathons, but I can't even run a mile.
Pro Tip 3/3
Habitual Actions
Often used to describe actions done out of habit, without much thought. He thinks nothing of checking his emails first thing in the morning.