Simple tool for managing life

I use this little idea (Not often enough though) for a better life.
If I have a thought I should ask myself is this positive or negative. Does this serve me or society is it destructive? Same with speech and actions. I try notice it and categorize it if its a negative action or speech dont do it. If its a negative thought let it pass or replace it with a positive thought or focus on the task at hand. For example if you have to speak to a mean boss focus on what you need to achieve from the exchange not your hate towards them. Same goes for Pron if you start thinking replace the thought or focus on something you need to achieve...
any thoughts?