Inattention
Attention is runs on interest, urgency, and novelty rather than on importance, so something necessary but flat slides off no matter how much a person wants to stay with it. Details get missed, instructions arrive in fragments, and the person called careless was often paying complete attention to something else more interesting
Hyperfocus
Given something genuinely compelling, attention locks in for hours at a depth most people never reach: meals skipped, messages unanswered, the afternoon gone. It is productive and the difficulty is usually getting out of it rather than getting into it.
Starting, switching tasks or transitions
The hardest part of a task is often beginning it, leaving it, or moving to the next one. Intention is rarely the problem. A person can want to start, knows exactly how, and are not able to move. Transitions are as difficult. changing space, an interruption at the wrong moment can be difficult to navigate
Procastination
Procrastination is delaying the start or the completion of a task, a paper, etc... Delay here is usually not avoidance of the task but a wait for the conditions that make starting possible: enough interest, enough pressure, enough adrenaline. It is why deadlines work and why nothing before the deadline does. The work often turns out well, which quietly teaches the pattern to repeat itself.
Time Blindness
Ten minutes and an hour can feel identical from the inside. Time is experienced as now and not-now rather than as a line with positions along it, so a future event stays abstract until it is suddenly imminent. This is a synchronization problem . The internal and external clocks run at different speeds. From the outside it rarely reads that way; it reads as disregard for other people's time.
Working Memory
The thing being held gets dropped mid-reach: the sentence you were about to say, the reason you walked into the room, the second half of the instruction. Working memory is among the executive functions most consistently shown to differ in ADHD across large studies. Ideas arrive fully formed and leave if they are not captured immediately, which is why external systems (to-do list, Calendar, reminders, etc...) are necessary.
Rejection Sensitivity
The sharp, disproportionate, almost physical pain of being criticized, corrected, It drives much of the over-apologizing, people-pleasing, withdrawal, and sudden anger that get read as personality, and it is frequently the reason someone quietly stops trying at something they were good at.
Sensory Sensitivity
Sound, texture, light, smell, and crowds arrive with the volume up. Part of why people with ADHD are often funny, perceptive, and quick to care is that they are taking in more of the environment. When the environment is loud or crowded, or the lights are flickering, the nervous system gets overwhelmed and triggers a fight or flight response. As a result patience can drop out without warning, people's fuse is a lot shorter