I've read that in order to retire you need 25 times your yearly expenses invested/saved.

I'm not sure I quite understand the math (not my best subject).

So during these 25 years, where are you pulling money from? I'm assuming dividend payouts, maybe interest?

Dividends I would understand if you were at a 4-5% yield but it seems most here are into index funds which seem to pay around 2% or so. At this time anyways.

What happens when the 25 years runs out and if you're making a 2% yield?