A lot of aches and pains are just made up by your brain. Modalities such as massages, foam rollers, etc… does nothing to you when it comes to actually healing your body or helping your recovery, but many people swear by it regardless.
Slight ache in your lower back? Depending how you mentally approach it, that pain may dissappear or get worse.
It’s why doctors have to careful about the nocebo effect, you might end creating a negative side effect for for your patient by just mentioning the potential side effects.