Shanahan came under fire after the defeat for several play-calls, including a pass on third-and-1 that led to a Matt Ryan fumble and not rushing the ball three times to set up a field goal that would have given Atlanta a double-digit lead late in the game.
Shanahan also was asked about a report that cited him saying "I blew it" after the game.
"I don't know if I used those exact words, but that sounds about how I talk," he said. "...I did believe we had a very good chance to win that game, especially at the end and we didn't get it done. When you use the words 'I blew it,' I don't look at it that way, I believe we missed an opportunity and we didn't get it done. I'll go back through every play for the rest of my life."
Now taking over the reins in San Francisco, Shanahan said the loss wouldn't linger because playing aggressive is part of his DNA.
"We played that game how we played the entire year," he said. "I called plays in that game the way I have the entire year. Doesn't mean I'm always right. Doesn't mean they're always going to work. But I promise you I prepare as hard as I possibly can. I always do what I believe is right, with our coaching staff and with the players, and then you live with the consequences.
"Yeah, it's going to be hard living with that loss. Every play that didn't work, I regret, as always. But I can deal with it because I can look at myself in the mirror and know I did what I thought was right at the time. And that was the most important thing to me. I didn't change because of a circumstance. I did what I thought was right. Whatever happens, if you do what you thought was right and you believed in that because of the preparation you had, you should be able to live with the consequences."
Shanahan's aggressive approach helped make the Falcons the league's best offense in 2016. The play-calls in the Super Bowl are easy to question in hindsight after they weren't executed on the field. As he takes over the 49ers' head gig, Shanahan won't lose his aggressive style after a historic collapse.