The 33-year-old actor, who is married to Demi Moore, said that people just expect happiness to come to them, but that is not the case.
Appearing on Lorraine, he explained, 'A good relationship will ground you. I think the key to any relationship is work on it when it's good.
'When things are going good a lot of the times people just rest. But we all have this assumption that at some point in our lives we will just be happy and we won't have to work on it anymore.
'And the minute you stop working on it is the minute things start to fall off. And I think in relationships and family, when it's really going good, work on it then, and it will stay good.'