I would blame no one for using keyboard macros instead of the in-game ones. (We all know that the in-game macros are crappy).

But here you go:

/macroicon "Physick"
/echo I Shall heal myself
/ac "Physick" <me>

Put it on your hotbar and then set up a keybind for the slot. Set the same keybind on your g-key as one button press and profit.