In an interview with "60 Minutes" that aired Sunday night, Vick said the day he walked into prison he realized "the magnitude of the decisions that I made.
"And, you know, it's no way of, you know, explaining, you know, the hurt and the guilt that I felt. And that was the reason I cried so many nights. And that put it all into perspective," he said.
A three-time Pro Bowl pick during six seasons with the Atlanta Falcons, Vick served 18 months in federal prison for running a dogfighting ring and was reinstated last month by the NFL after being out of action since 2006.
He signed with the Philadelphia Eagles on Thursday.
"I let myself down, you know, not being out on the football field, being in a prison bed, in a prison bunk, writing letters home, you know," he said. "That wasn't my life. That wasn't the way that things was supposed to be. And all because of the so-called culture that I thought was right - that I thought it was cool. And I thought it was, you know, it was fun, and it was exciting at the time. It all led to me laying in a prison bunk by myself with no one to talk to but myself."
Vick said he blamed only himself for landing in prison and deserved to lose the $135 million contract that made him the NFL's highest paid player.
"I was disgusted, you know, because of what I let happen to those animals," he said. "I could've put a stop to it. I could've walked away from it. I could've shut the whole operation down."
Vick said he initially lied about being involved in dogfighting because he realized his career was in jeopardy.
"I felt the guilt and I knew I was guilty, and I knew what I had done," he said. "And, not knowing at the time that, you know, actually telling the truth may have been better than, you know, not being honest. And it backfired on me tremendously."
Vick also admitted that his reputation as a player that didn't work hard and relied mostly on his athletic ability was warranted.
"I was lazy. You know, I was the last guy in the building, first guy out," Vick said. "I know that. You know, I hear everything that people say. And that hurt me when I heard that, but I know it was true."