“Protecting your energy” can be a useful shorthand for caring for your attention, time and emotional effort. It does not require believing that another person transfers an invisible substance into you.
Name the interaction
Instead of deciding that someone is negative, describe what happened. Did they interrupt, demand more time than you had or repeatedly ignore a limit? Specific behaviour helps you choose a response without treating a feeling as proof of their character.
Decide what belongs to your role
You can care about someone without solving every problem. Ask what you are able and willing to offer. “I can listen for a few minutes, but I cannot take this on today” is a boundary, not a punishment.
Take a practical pause
Step away when possible, finish the conversation or return to an ordinary activity. If imagining a boundary helps you remember your choice, use it as a metaphor. There is no need to send harmful energy back or test whether you can block a friend’s energy.
Review recurring patterns
If the same interaction leaves you depleted, consider a shorter visit, a different topic or support with the situation. You do not have to blame yourself for being affected, and you cannot control another person’s behaviour by staying positive.
After an interaction, record the behaviour, its impact and one boundary for next time. This creates a more useful record than labelling people as inherently toxic based only on a mood or hunch.