"I thought I was ready once before, but I wasn't," Chesney, 40, said of his 4-month marriage to Renée Zellweger in 2005. "If I get married again, I'm going to give it 150 percent."
The pair have remained close friends – Chesney even tells PEOPLE's Country Special that she is "the sweetest soul I've ever met" – but he admits it was hard to cope with the split.
"There was nothing that made me happy," he said. "You can't fall in love as hard and fast as we did and not have some residual effects."
Chesney, who was named entertainer of the year at Sunday's Academy of Country Music Awards, added that he looks at it "as a life lesson." Not to mention: "This is the happiest I've been in a long time."
For more on Chesney, pick up the June issue of PEOPLE's Country Special, on newsstands now