"The last five days, I've been waking up with the same realization, and it takes a couple of seconds to realize it really happened," Epstein said. "That's the mode I'm in right now, appreciating and feeling really lucky to have been part of two great franchises when these historic things happen."
Epstein, who talked to reporters in Phoenix on Monday at the start of the General Managers Meetings, helped end the Red Sox's 86-year drought in 2004. Last week, the longest championship drought in professional sports finally ended as the Cubs beat the Indians in a dramatic seven-game World Series.
Of course, the question now is, can the Cubs do it again?
"It does make you hungrier to validate it," Epstein said about winning the first championship. "Our fans have waited a long time. It's something that would mean a lot to us."
"We're going to continue to build around that," Epstein said. "We have so many young guys who are just coming into their own. I feel this nucleus is going to stay intact."
Epstein has acquired several important players through trades, including Rizzo, Arrieta, Hendricks and Russell. The trade for Russell in July 2014, which sent Jeff Samardzija and Jason Hammel to the Athletics, is the type of deal Epstein hopes he doesn't have to do again.
"When we made the Russell trade, we said we hoped this was the last time we were going to make a trade of this nature, to take away from our big league team purely for the future," he said. "Those trades were really important in bolstering our efforts. It's hard to do it through the Draft alone or the international market. Those trades really gave us some momentum."
Since he took over the Cubs, Epstein has stressed his goal to build a foundation for sustained success. The young players are key.
"If you win with a bunch of older players with expiring contracts and things, maybe you need to replenish a little bit and make some trades before the guys walk away for nothing," Epstein said. "If you're lucky enough to win and have some continuity and a nucleus that's going to be around for awhile, you absolutely need to continue prioritizing winning."
Can the Cubs reach the same status as other perennial playoff teams?
"We'd love to be the type of organization that national baseball fans think of when you think of October baseball -- the Braves, Yankees, Red Sox, Cardinals," Epstein said. "We've got two [postseasons] in a row now and one championship. We'd like to be there every year if we can and take our shot. We're lucky to have a lot of talented young players, great manager, support ownership, terrific fan base as resources.
"We'd like to see how sustained we can make this success," he said. "Our fans deserve a long run if we can possibly do it."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.