That's right, we're going to flip the Golden Rule on its head for fun and profit. The Golden Rule, remarkably, has its share of criticism. (George Bernard Shaw says, "Do not do unto others as you would that they should do unto you. Their tastes may not be the same.")
I have developed enough metacognition over the years to realize how harsh my tone has been with myself. Maybe you've found similar awareness. I developed a more compassionate voice to myself after reflecting on my tone in old journal entries ("Why do I even try? This isn't going to work. I'm a wreck.") and thinking more about how language is consciousness and vice versa ergo harsh words are literal psychic damage.
If, for instance, a friend doesn't meet their running goals for the week, how would you respond to that? Would you tell them they should give up and not try again? Would you say, "Put your damn shoes back on and MOVE!"? Probably not, for one reason or other. Why should you talk to yourself like that?
If a friend isn't feeling motivated to do anything, would you yell at them and call them names until they did something? Probably not.
I hear and see people I know advocating very intense self-discipline, to the point where I worry about them. As if their own inner parent were very strict with their schedule, their diet, their house rules. If you've got enough structure in your life to support your basic needs, why continue to push discipline? Who is it really benefiting? Maybe you could convert that punishment into nurturing guidance?
I think one reason for harsh self-talk is that it's hidden to others. No one else can hear and then judge this self-talk, and so it can devolve into verbal abuse. If you verbally abused a friend you'd see their confused and horrified face and maybe anger and retaliation. You don't see such negative feedback when rudely addressing yourself in your head. So here I am offering that negative feedback: cut it out.
Maybe this is too Barney & Friends to be taken seriously, but wouldn't you like to be your own friend? I think you're worth it, and I'm not even trying to take your money.
Maybe I'm too firmly rooted in idleness movements for today's hustling and bustling society, but I firmly believe you should cut yourself some slack. You'd do this for others. Why not do the same for yourself? You're worth it.