This will remind you how many things we take for granted.
→ Is this grammatically correct and natural?


1. I'm sorry I zoned out. What did you just say?
2. I'm sorry I spaced out. What did you just say?
→ Are they grammatically correct and natural?
→ Are both "zone out" and "space out" identical?

See a translation

"This will remind you how many things we take for granted."

It is, for the most part, grammatically correct, but you must say "this will remind you of how many things" because you must bridge the relationship together with "of" for it to be correct.

For your next two sentences, they are grammatically correct and natural. You may even bridge together the two sentences because they are simple independent clauses "I'm sorry I space out; what did you just say?"

"Zone out" and "space out" are synonyms, so they are identical.

Brilliant work, Kevin!