He told E! Online: “I’m constantly reminding myself, like, no matter how amazing my relationship is, keep working on it. Keep working on it and keep finding another level. Things can always get better, even when it's going great."
As well as always working at his relationship, Ashton recently revealed he prefers to declare his love for Demi online.
The actor thinks using social networking websites to send affectionate messages to his 48-year-old spouse is no different to sending flowers to the workplace.
He said: "Sending sweet nothings on twitter or Facebook is fun. In some ways, it's no different than sending flowers to the office: You are declaring your love for everyone to see. Who doesn't like to be publicly adored?"
Although Ashton loves to declare his affection for wife Demi online, he admitted a computer is no substitute for human contact.
He said: "When someone needs us, he or she needs all of us. There's no text that can replace a loving touch when someone we love is hurting."