Got to agree with all the above comments!
I flew SLF on B737, MD83, B757 then B767's for 20 years - I can't say I didn't have a great time because I did - it's an ok lifestyle particularly when your a single guy. I opted out of the SLF world post 9/11 and I've been flying B757 freighters on European routes ever since.
The pilot turnover in the freight company I work for is high and I've seen a lot of newly qualified professional pilots come and go, (grass is greener and all that) but most of the experienced guys seem to know which lifestyle they prefer!
There are a lot of flying opportunities out there just now, so my advice to anyone would be "go and fly passengers first" - get the hostie thing out of your system and then join a freight outfit - you'll view the lifestyle thing more clearly!