I read the OPs intention as "use K to get the person back from the bottom of depression and then leverage that boost in mood to start a habit of excersize"
That seems reasonable and a good approach. You want to reinvest the motivation and better mood into relationships and behaviors that will continue to compound feeling good.
I'd also recommend Gratitude as a practice and ultimately some sort of somatic work where you are encouraged to go deeply into any uncomfortable feelings with your full body.
I get where you're coming from with this response - if you haven't been there, there is just no way you can understand how desperately bleak things can become.
But if someone is ignorant about mental health, why not try to educate that tell them to "shut up"?
We need to talk about these things, not humiliate and shut down anyone who doesn't understand.
Nothing is more irksome than the trend in public discussions to tell others to "shut up" if they haven't specifically experienced something.
This is a public forum. We're discussing a publicly posted article. The OP brought to the table a valid point. Let them talk.
If the answer is zero (which I think it is) do those who have it a favor and shut up. Depression is hard enough without "you just have to exercise, huahua" comments.