The concept of mental subtraction is not all that hard.
If you are feeling depressed, imagine what life would be life if you lost the use of your limbs followed by the loss of your senses like sight, smell and hearing. Compared to your current life, these scenarios would be truly depressing so naturally, after performing this exercise, you become a lot happier.
The actual reality is different from this mental exercise because we acclimatise ourselves to our good fortune and misfortune. Disabled folks rapidly become as happy as their non-disabled selves. Folks who win the lottery often find that their happiness short-lived.
I can't really say that tossing myself into workshop training fresh from being admitted to the Singapore Bar is an act that will makes me unequivocally happy. It's a highly risky act which flies in the face of common sense and goes against "doing the right thing". ......