"I'm afraid. But I'm out here because I'm afraid," the ex-analyst told an audience at The New Yorker Festival in New York.
"I've had people telling me, 'Maybe you shouldn't be so vocal.' And that's the reason why I'm out here," she said, explaining that she "can't imagine doing anything else right now."
Sentenced to 35 years in prison in 2013 for leaking over 700,000 classified documents related to the wars in Iraq and Afghanistan, Manning served seven and was freed in May after Barack Obama commuted her sentence days before he left office.
"I had this image of going (back) to a life that I had before. And that's not possible. And I realise now that that's OK," she said.
"Things are really scary right now and I don't want to be retiring right now."
Seven years after embarrassing Washington with the leak, which included over 250,000 diplomatic cables, Manning also expressed her belief that governments are too secretive.
"Why do we have governments to keep secrets? They keep secret from the public mostly. There's this excuse that governments use -- 'it protects this' -- that's being used as a blanket," she said.
"Where I think the line should be? I think we need to decide, not the government."
Manning also urged the general public to be cognizant of personal data protection online.
"I think we do understand it," she said, referring to the uncontrollable circulation of personal data on the internet, adding the problem is "hoping that someone is going to fix it for us."
"They're not going to fix it for us," she insisted.
