What is free will?

Great discussion with a lady running for political office yesterday.  She was explaining to me how cannabis(sp?) was not a sin, citing Gluttony with Little Debbie cakes, Smoking and tobacco use as legal, and you can't legislate morals, example phohibition.  I thought on that all day yesterday.  It reminded me of when I first got saved!  The Bible was 90% correct day one!

I thought on the weaker brother and how one person might be able to do something and it worked for him, yet, another might "stumble" with it...

I read in that Bible, "work out your own salvation...."... but when I hear free will means we can do what we want, we need to share some verses.  tune in!