Michelle Obama says she rarely ventures into the West Wing to dispense policy advice to her husband -- and sometimes holds back from talking shop when the president has finished work for the day.

In an ABC "Nightline" interview airing in part Monday night, the first lady said her attention is focused on her own projects. She has taken the lead on issues such as reducing childhood obesity and supporting military families.

"I rarely step foot in the West Wing," Obama told "Nightline" anchor Cynthia McFadden. "In fact, people are shocked when they see me there. I rarely walk in that office because the truth is, he's got so many wonderful advisers. He's got a phenomenal cabinet. He's got people who are in the trenches on these issues every single day, and I'm kind of stepping in and out, and I've got my own set of issues. So I don't even have the kind of expertise and the time in to be able to provide the kind of advice and guidance that he's already getting."

Though she stays out of the West Wing, Obama has been utilized widely on the campaign trail. A Bloomberg analysis last month showed she had raised at least $17.5 million over 56 fundraisers, and that number has increased since.

And while the first lady holds degrees from both Princeton and Harvard Law School, she said she sometimes holds back from peppering her husband with criticism or concerns in the residence.

"In a job like this, the last thing the president of the United States needs when he walks in the door to come home is someone drilling him and questioning him about the decisions and choices that he's made," she said. "There are definitely times when I may feel something, but I'll hold back because I know he'll either get to that on his own or it's just not time."