compression of a two hour m4a recording

I was recently at a conference and used voice memo from the iOS9 built ins on my iPod to record the lecturers. I have some very large files that I would like to distribute via email. Any suggestions on an app, preferrably free, or how to use any of the built ins from my macbook pro or iMac using the latest operating system to compress these files to a 35MB file so I might share? They are more than twice this size now.

I will say that I attempted the Compress drop down in Finder and it made it a couple of MBs smaller. I have looked around and maybe I am using wrong search criteria but I am hitting a wall. I will say that I would rather not use sendspace or hightail to send these files. Any help would be appreciated.