"He had nothing else, I guess," Day said with a laugh about Woods, who hasn't competed in more than six months after two additional back surgeries. "He was just sitting at his home and I just called."
Their conversation lasted about 50 minutes, according to Day, and Woods was steadfast in his advice to the world's No. 2 player.
"Every time that I talk to him, it's mindset, mental toughness, effort," Day said. "It didn't matter how bad it was; if it was a course that he did not like, he was just going to flat out-execute you. It did not matter. That's that killer instinct that I need to get back like I had at the second half of last year, get back and take it into this year and go through with it."
Last year, Day won five PGA Tour titles, including the PGA Championship, and four times in the final three months of the season.
"I have the killer instinct -- I do, it's down there, but it just hasn't come out yet [this year]," he said. "Once it does, I'm hoping that I can replicate the second half of last year. But it's amazing to be able to talk to someone that's done it for so long, because [Woods] did it for 14, 15 years of just absolutely dominating and killing it. If there's a better person to talk to about it, that was him."
Day explained that last year's success, which lifted him to No. 1 in the world for four weeks, has led to greater expectations -- both internally and externally.
Dealing with those expectations was another reason for his phone call to Woods.
"That's one of the main reasons why I called Tiger was to ask him about stuff like that, because he dealt with it so great and he wanted it for so long, and that's the biggest key was want," he said. "It really comes from within. But once again, I'm talking to Tiger about it and just I have to make sure that I go out there and go through the process right and do all the little things that got me to that point of dominating the second half."
In three starts this year, Day has finishes of 10th place, 11th place and a missed cut at the Farmers Insurance Open.