My computer is "hardened", security-wise, because computers are one of my interests so but I've always gotten spam email about things I've searched. No matter which search engine or email I use. BUT, I also get spam about things I THINK about that can't be connected to me via my internet activity.

It's a bit disconcerting, at first, because it's like somebody's reading your mind or your email but it's you - you are reading your own mind and manifesting evidence of the connection between your mind and your 3D experience.

Just play with that a while and pay attention as it expands to other "coincidences" around other matters.

You already have the idea because I just gave it to you so all you have to do is notice when it happens. Don't try to convince yourself they're "manifestations" - just notice coincidences and call them "coincidences" and pretty soon you'll have a big pile of coincidences that will collapse under its own weight.