WTH did Biden mean by "I had no intention of running again. I just lost part of my soul." during his address at the DNC (DUNCE?) tonight?

"(after Charlottesville) I could not stand on the sidelines. So I ran. Cause I had no intention of running again. I just lost part of my soul. But I ran with a deep conviction...in America...I know and believe in an America where honesty...dignity...decency...still matter. An America where everyone has a fair shot...and hate has no safe harbor... 81 million voters voted for us...more than any time in all of history...we came together in 2020...to save democracy."