Let us assume that nothing is wasted in life.
To be sure, let us define “wasted”.
If an action does not affect the achievement of the goal, then performing that action is “wasted”.
Everyone is free to set their own “goal”.
Because it is their own life.
Suppose a person sets a goal “do nothing wasted”.
In order to achieve the goal, they examines whether the act they is about to perform is wasted, and if it is, they does not perform it.
Since nothing is wasted in life by the assumption, if one examines whether it is wasted or not, it becomes “not wasted” and any action will be performed.
From this fact, the act of “examining whether or not it is wasted” does not affect the achievement of the goal “do nothing wasted”, so it is “wasted” by definition.
This contradicts the assumption that “nothing is wasted”.
Therefore, the assumption “nothing is wasted in life” is incorrect.