(1) Well, all joking aside, let's get to work.
(2) Joking aside, we really must do sth.
(3) In all seriousness now - joking aside - I do think there's a problem here that we've got to get sorted.
(4) All joking aside, I think you're crazy.
(5) Joking aside, I mean it.
(6) Joking aside, it to cost me a fortune to get it fixed.
(7) Joking aside , although the conditions were not very comfortable, we had a wonderful time.