You say yes before the question is finished. Your sister asks if you can cover Thursday, and the word is already out. The pharmacy calls, a neighbor wants a ride, the doctor's office asks whether you can come in early, and you hear yourself agree before you have looked at the week. If that is happening, you are not a bad sister or a weak daughter. A hundred small emergencies have trained you to answer first and check later, and the habit has started making your decisions for you.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
How to tell it has happened
Look at the last ten things you agreed to this month. For each one, answer three questions on paper. Who asked? Did I want to do it, or did I just not know how to say no fast enough? Would I have said yes if I had ten minutes to think?
If most of the answers are 'not fast enough' or 'no,' the yes is no longer yours. That does not mean every request was wrong. It means you have not been the one deciding, and that is worth fixing even when the requests are reasonable.
Put a pause between the question and the answer
The fix is not a hard no. It is a pause you can say out loud. 'Let me check my week and get back to you by tonight' is a complete sentence. So is 'I can do Thursday morning, not afternoon.' Use the pause for every request for one week, including the ones you would have happily taken. The point is to find out what you would have said.
When you check, compare three things before you answer. First, the real hours the task takes, including travel, parking, and waiting. Second, the commitments already on your calendar that week. Third, whether anyone else on the family list could take it. If a sibling, a hired helper, or a friend can take it, ask them first and let their answer stand.
Check which yeses are actually owed
Some care tasks are yours because the arrangement says so. Others are yours only because nobody has said otherwise. Make two columns. In the first, list what you agreed to in writing or in a family meeting. In the second, list what you have simply absorbed. The items in the second column are the ones to renegotiate first, because nothing binds you to them except habit and everyone else's silence.
Say the new answer once and keep it
When you change an answer, do it once, plainly, and do not explain for ten minutes. 'I am not able to do Saturday runs anymore. I can do Tuesday, and I need someone to cover Saturday.' Then stop talking. People will push. You can repeat the same sentence. You do not need a new reason each time.
When the automatic yes is about your parent
Requests from the parent are the hardest, because a no can feel like a refusal to love them. Treat the request as a question about the care plan, not about the relationship. 'Dad, I can take you Tuesday. I am not free Thursday' is a scheduling answer, and it can still be kind. If a request involves medicine, a fall, or a change in what your parent can do alone, that goes to the doctor or the care team, not to your gut at the kitchen counter. You do not have to decide those alone.
What to do this week
Pick one request you would normally agree to by reflex, and wait until the next day to answer. Write down what you would have said and what you actually said. Do this for five requests. By the end of the week you will know which yeses were yours and which were habits, and you will have a short list of people who can take the rest.
If the parts of the plan that keep landing on you need a wider look, start with Permission and a Plan. If you need names of help in St. Louis to split the requests with, see Local Help for Caregivers in St. Louis.