Arnold Schwarzenegger thinks he tried ''too hard'' to work alongside Sylvester Stallone in the past.

The 'Terminator' star and the 'Rocky' actor - who teamed up for action movie 'The Expendables' in 2010 - are reuniting for forthcoming action-thriller 'The Tomb', and Arnold believes it is now an ideal time to collaborate with Sylvester.

The 64-year-old former Governor of California said: ''We worked really well together. The funny thing is we have tried, I think, our entire careers to always work together.

''We have talked about it for three decades and it never happened. I think we tried maybe too hard ... But now after the governorship, somehow this just fell into place.''

Sylvester admits the pair were ''competitive'' when they started their respective acting careers, but they have both now realised that teaming up with one another is beneficial.

In a joint interview, the 65-year-old actor added to ET Online: ''We're just a couple of old war horses talking about the oddest subjects on the planet.

''I think in the beginning we were competitive - there's no question about it. A little alpha territorial. And then we realised it was good for our careers [to work together].''