The quote "my mind is going" is from the script of "2001 - A Space Odyssey", said by the AI named "HAL" when his circuits are being disconnected. Donald Trump should say the same, but he is already too far gone to notice his own decline. Anyone observing his behavior, though, can clearly see a man already far into the fog, losing himself to senility.
At today's press briefing, Trump appeared in a brief pre-recorded video message which was edited from several even shorter snippets, apparently to hide the fact that the president can't speak for a couple of minutes without hitches. Even so, he managed to come across as seriously senile. He didn't look at the camera, he had absolutely no mental presence in his delivery of the speech, and he appeared to have some problem with keeping his right eye open. The video showed a person in very bad shape.
This man is incapable of doing his job, or indeed any job. He needs to be fired.