Bryan Cranston advised Jon Hamm he will find it ''hard'' to let go of 'Mad Men'.

The 44-year-old star recently shot his final scenes as Don Draper in the advertising drama and the former 'Breaking Bad' star warned him that coming to terms with the ending of the show won't be easy.

Bryan told Jon: ''It's hard, man. It's hard to let it go. It'll hit you a couple of different ways at different times.''

Jon has played Don for seven seasons of the show and admits it has been draining documenting the creative director's downward spells, but also a rewarding experience.

He told the new issue of GQ magazine: ''You're kind of hoping for redemption, and it's not forthcoming.... To consistently come in and be the bummer was always like, 'Oh, that's not fun.' But at the same time, it's been like the greatest obstacle course in the world. A puzzle to figure out.''

And the actor's long-term partner, Jennifer Westfeldt, thinks he felt relieved when filming came to an end because the character has ''weighed heavily'' on him.

She said: ''It's a confusing juxtaposition. I think the darkness of Don has weighed heavily on Jon, despite it being the role of a lifetime and the opportunity that gave him the career of his dreams.

''The end was of course bittersweet and complicated for Jonny.

''But I know that when he wrapped the show in LA, in the wee hours of July 3 last year, and then immediately got on a plane to New York to meet me and our dog, Cora, for dinner with a few close friends and to watch the fireworks, he felt a predominant sense of relief.

''He remarked on the cosmic coincidence of the date: Independence Day. Finally.''