40% of your earnings is too high of a target. Normal people receiving minimum salary will have a hard time keeping up and will frustrate them. Soon they will stop saving because of that. It is better to save small percentage but can be consistently done without straining too much your budget.
Yup, 40$ was too high, not all of us is high earners where we could keep almost half of out salary, mostly we just receive enough salary so keeping 40% of it might just compromise your living or might result to problem... I think computing about how much you will save should be after buying all your basic needs, the leftover money should be the target of our savings, that's the money where we could mess around whether we are going to save it all or spending it to something else...