The way I read it is that we do have control over our emotions, as that is how we react to external stimuli. We can control or reaction to events.
But feelings are a deep rooted, take time to build, and therefore are not controllable in a singular event.
i.e. - emotions are the little boats, we can turn them on a dime, if the wave causes us to tilt to much, we can adjust how we point the boat when the next wave hits and have less impact.
Feelings are the big cruise ships, they take forever to change course, you can't change course because a wave is coming so every "wave" has a similar impact.
If someone asks me on a date, but when I show up they stand me up, I would be upset and really disappointed because I was really looking forward to meeting up with them. The next time they ask me out, I decide that I'm gonna have a drink, strike up conversation with someone at the bar so if they don't show up, I didn't waste my time... they don't show up, but I'm not as upset (my emotions).
After getting stood up hundreds of time (no, I'm not that gullible), my feeling is that when asked out, I can expect to get stood up. When I get asked out next, they show up, but my deep down feeling doesn't just change to expecting people to show up when asked out, it would take a while of someone showing up to change my overall feeling.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized