People with ADHD often struggle with saying "no" to requests or demands from others, and may find themselves saying "yes" even when they don't have the time, energy, or resources to follow through. There are several reasons why this may be the case:

1. Desire for approval: People with ADHD may have a heightened need for approval and may worry that saying "no" will result in rejection or disapproval from others. They may fear that saying "no" will make them appear uncooperative, unhelpful, or uncaring, and as a result, they may feel pressure to say "yes" to everything that is asked of them.
2. Difficulty with decision-making: People with ADHD often struggle with decision-making and may find it difficult to assess the demands on their time and energy. They may have difficulty prioritizing tasks or determining which requests are most important, and as a result, they may agree to everything out of a sense of uncertainty about what they should be doing.
3. Fear of missing out: People with ADHD may have a fear of missing out on opportunities, experiences, or social connections, and as a result, they may say "yes" to everything to avoid the possibility of missing something important or exciting.
4. Impulsivity: People with ADHD may act impulsively, saying "yes" to requests without thinking them through or considering the consequences. They may feel a sense of excitement or urgency in the moment that makes it difficult for them to resist saying "yes," even if they know they may regret it later.
5. Difficulty with time management: People with ADHD may struggle with managing their time and may find themselves overcommitted as a result. They may have difficulty estimating how much time a task will take, and may take on more than they can realistically handle.

Overall, people with ADHD may struggle with saying "no" for a variety of reasons. It is important for individuals with ADHD to learn how to set boundaries and prioritize their time, and to communicate their limits to others in a clear and assertive manner. Therapy and coaching can be helpful in developing these skills, as well as in improving decision-making and time management abilities.