A friend’s intuition
If you notice that a friend is acting unusual, it’s a good idea to reach out to them. They might be going through some things that are weighing down on their soul or much, much worse. In this case, the friend was in the midst of a heart attack, and nobody, not even the friend, knew it.
The OP noticed that his coworker was behaving a little odd that day. Not only did he not know how to perform the simplest tasks, but the figures in his spreadsheet resembled nothing like his normal work. This spooked the coworker enough to see a doctor after work that day, which ended up saving his life.