How to be original when writing music these days?

I've written hundreds of songs from guitar riffs I came up with, or at least I thought I came up with. When it comes to writing clic style and punk songs, which is what I love to write and play, it is hard to be original, especially after hearing a good 2000 songs in that genre, from the most obscure of bands who played 10 shows and released a 7", to famed bands like Dead Kennedys. Every time I come up with a riff, it's "oh yea, I heard that one in that song ____ by _____". I think every single possible riff has been come up with and copied over the years. But I can't see myself playing anything but good old punk, since I love it with a pion. How can I be original?