What did Donald Trump do today?

Twitter, in ways that he'll probably regret.

Trump has spent the work day on what is an epic Twitter-binge even by his standards. He had already tweeted a record 108 times as of 2:30 EST. But one in particular stands out. Trump attacked 16-year-old climate activist Greta Thunberg, who yesterday was announced as Time's "Person of the Year."

Trump often uses Twitter to distract from other things he's doing, or because he thinks it will score political points. That doesn't seem to be the case here. 

Instead, Trump's tweet came from genuine hurt and anger that he was not selected as "Person of the Year." (In fact, his outburst was widely expected and predicted in advance by pundits.) 

Trump, who at 73 years old may remember the magazine's glory days a little better than Thunberg, has long used it as a barometer of his self-worth. He's claimed to have appeared on its cover more than anyone else—which was a lie, even ignoring the fact that many of those covers showed him in a completely negative light. In 2017, he explained away not being named "Person of the Year" by saying he'd taken himself out of consideration—another lie. (The magazine doesn't ask permission, and sometimes chooses people whose influence was totally negative.)

Trump even made up a fake Time cover, featuring his own picture and with a headline calling his reality TV show The Apprentice a "smash," and then hung it on the walls of his luxury golf resorts. (Just last month, a Trump political appointee to the State Department with fraudulent credentials that included a fake Time cover of her own was forced to resign.) 

Thunberg, who has been insulted by Trump before, responded the same way she did the last time: she made Trump's tweet her Twitter bio.

Why does this matter?

• Emotional outbursts, inappropriate hostility, overreaction to perceived slights, and projection are all signs of a serious mental health problem. 

• There were probably more important things for the President of the United States to be doing with his Thursday than sending out hundreds of tweets.