Cut back on relationships that drain you, and learn to turn down requests you don't want to take on

Moderate value
Evidence C
Saves time
Free
Takes minutes
Long-term effort

In plain words

The damage done by one person who drains you is greater, and more consistent, than the benefit from one person who supports you. So subtract first, then add.

Cost: Free. In the short term there will be social friction, and you may lose some relationships. Saying no takes considerable willpower.
What you get: A survey of 120 widowed women aged 60 to 89: the link between upsetting interactions and psychological well-being was more consistent and stronger than the link for pleasant interactions. By this result, the damage from one person who drains you is greater than the benefit from one person who supports you.
Notes: The group surveyed is unusual, and it was a one-time questionnaire, so it cannot show what came first. It measured well-being, not energy. Placing it in this section is the author's inference. There is no objective standard for which relationships count as “draining”; you have to judge for yourself.
Evidence grade: C : The author's experience or common practice, without direct literature.
Sources: Rook (1984). The negative side of social interaction: Impact on psychological well-being. Journal of Personality and Social Psychology. https://doi.org/10.1037/0022-3514.46.5.1097

Translated from the Chinese original. Original book, section 3, tip 16. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer