If we always say "yes" to others, we are saying "no" to ourselves. We lose sight of our own priorities and instead live by other people's standards. Saying "no" at first may bring feelings of guilt. But "no" is just a word.
You may find it difficult to say no or may fear to disappoint the other people. Because of this, you may try to find lengthy excuses for why you can't help with their request. You don't owe an explanation, but it can feel easier to give one.