Pick your moment: send it during a calm window (morning/early evening).
Make it specific: “One thing I can do this week?” (school run, form, call, pick-up).
Do it and close the loop: complete the task, then send a short done + when update.
Message one person now: “One thing I can do for you this week?”
Don’t over-promise; choose tasks you can finish. Share limits kindly (“I can do X by Friday, not Y”). Rotate who you ask so it’s balanced.