Captain Cankles boasts that he's very good physically & mentally in advance of his SECOND "annual checkup"

[Bernardo de La Paz]

4. He is of two minds about it: 1) His primary skill, 2) He knows he's not well

1) He knows the public is "concerned". He wants to continue to prop up the manly man strongman image, because it does incrementally help him in his base and wobbly purple areas.

2) It is yet another slip-up where he acknowledges his impending mortality. Why does he focus on this? Rather than, say, his golf game (aside from issues of sloppy scorekeeping contrasted with the awesome responsibility of the Oval Office).

He is worried he's losing his grip. He is worried about his legacy. He knows he's losing his edge. He knows he's sundowning, on a downward slope that he can't be rescued from.