It's the burden of command. It doesn't always stop him from goofing off with his crew, or coming up with some silly way to make them all feel better. Hell, he drug a Christmas tree onto the ship one time and set it up in the rec room, at the same time inviting other members of the crew who celebrated from different cultures and worlds to come and share it.

"I know." This isn't what they signed up for. Not in the least. He lets his hand drop down, and clasps his hands in his own lap. "Chekov, you've got nothing to prove to me. And whatever these people on this ship think, it's nothing. I've seen you in action. I've seen you take on a job you weren't sure you could handle and perform far above any expectations I might have had." He'd written out reports for what he remembered while he was recuperating, but much of the crews actions had not been witnessed by himself during their freefall to Earth.

"You took on a big job. You took care of the ship, the crew, and you didn't falter." He hasn't said it, not in so many words, because it's difficult to get out. There was so much he didn't get to say, to everyone, when he was stuck in Main Engineering. "You made me proud to be your Captain."