File size for podcast too large?

I am trying to find out how to compress my podcast file to help with download speeds. It is a mix of music and me talking. I first convert the songs in iTunes to mp3s, then import them into Garageband. I usually use 3 tracks in Garageband (one for my voice, 2 for the music tracks blending). I then import this to iTunes, convert the file into an mp3 and upload that file to my hosting site (ourmedia, it's free)

The podcast is @ an 45-55 minutes long. The file comes in around 70-80mbs. It takes a long time for people to download, duh?!

My question is, is there a way to compress this or am I missing a crucial step? I have checked some other 1hr podcast files that I subscribe to and they clock in around 27mbs. I am also thinking of paying for hosting on godaddy.com. Suggestions?