“Our envy always lasts longer than the happiness of those we envy.”

Envy can be a good motivator, don't you think? But if all you do is stew or think hateful things about someone you envy, that is poison.

I guess it depends on what you are calling 'envy'. Webster's defines envy as "ill-will or discontent at another's well-being or success.
synonymous with:malignity, resentment, spite.

It is kind of the opposite of admiration, I think. I am not sure envy , as defined, serves us well. However, I suppose there is quality it can spark that motivates. I think on balance the harm is greater than the reward.

Maybe what I meant was admiration. I was thinking more of a "discontent" than "ill-will". The discontent being a motivation for someone to make a change.

Thanks for your thoughts.