This isn't strictly true. Multiple studies have shown that coffee reliably acts to increase alertness and can often boost mood.

Alertness isn't the same thing as energy, which is why people who drink a lot of coffee often feel tired but "wired". The brain is alert but energy is low. Abstaining from coffee can "reset" the nervous system to an extent, but alertness and energy is largely determined by insulin levs in the body. So figuring out what works for you with diet is a much better way of getting more stable energy through the day, regardless of caffeine intake.