Ben wrote:

I moved into my house not too long ago and had the first occasion to
want to go up to the roof yesterday. It looks like there are three
layers of shingles. I've read that you should never have more than
two layers of shingles because of the weight. How much should I worry
about this?

Thanks for your input,
-Ben

Before doing anything else, confirm that you DO have three layers of
shingles.

It sounds like you don't have much experience examining roofs (and
there's nothing wrong with that ) so get a roofer or other
knowledgeable pro out to confirm. THEN decide what, if anything, you
should expect from, or need to do to, your roof.