TODAY | January 16, 2014
>> kristen, what's on tap?
>> reporter: for days they've been gearing up for a big day at the white house . guests were told to wear comfortable shoes and to be prepared to move around a lot. an indication there will be no shortage of dancing here. the buzz about the first lady's birthday party , possible performances by adele or beyonce, who has dazzled for the first family before. at last
>> reporter: but for now saturday's plans are top secret . what is known, president obama is playing the role of planner in chief after the first lady threw a big 50th bash for him three years ago.
>> you do get the sense his competitive juices are flowing.
>> reporter: just back from an extended stay at oprah's house in hawaii, a gift from the president, the first lady seems to be taking up the big 5 -0 in stride, opening up to "people" magazine.
>> i've interviewed four first ladies and i've never seen one so candid and relaxed about such a personal thing. she is dancing into her 50s.
>> she said turning 50 brings her a certain sense of confidence. her message to women, be heathy. i have never missed a mammogram.
>> she's incredibly frank.
>> the plans for her big milestone are under wraps.
>> i asked the president if he could whisper if my ears. he said it's top secret , not even the nsa knows that.
>> reporter: turning 50 and in addition to wearing comfortable shoes, guests were reportedly also told to eat first.
>> i'm liking the dancing part.