If only you could command your brain to actually do that. It would be cool to have some kind of remote control to switch off your thoughts. Thoughts off, Siri. Or, more positive thoughts, Siri. Forget about this thought, Siri. if only.
There is a moral imperative to seeing mental health through the same lens we use for other pathologies or illnesses. Being sad or overwhelmed is normal, much as being short of breath after a run is normal. Both become abnormal when they happen with no apparent cause and are hard to stop. Those situations need medical attention.