"We're out on tour to win tournaments and to win titles every single week, but tennis can be really tough where you sometimes lose a lot," said Pegula, the 29-year-old American seeded fourth.
"Even when you're winning a lot of matches, you're still not winning tournaments, so it can get tough. Winning a week like this week makes it all worth it and makes you want to keep going for more."
She topped Samsonova in 49 minutes after the 15th-seeded Russian beat third-seeded Elena Rybakina of Kazakhstan 1-6, 6-1, 6-2 earlier Sunday in a rain-delayed semifinal.
"I know, obviously, physically she wasn't feeling her best, but at the same time I played a really clean match," Pegula said. "I don't really think I made any unforced errors or anything. I played kind of a perfect match."
Pegula is the first American to win the event since Serena Williams in 2013. She beat doubles partner Coco Gauff on Friday in the quarterfinals, then knocked off top-ranked Iga Swiatek 6-2, 6-7 (4), 6-4 on Saturday in the semifinals.
"Beating Coco and beating Iga were two really tough wins back-to-back," Pegula said. "And being able to do that and then just come out today and play a really clean match was kind of great. I felt like I didn't have a ton of pressure at any point or I wasn't worried too much today."