There's more than one type! Some people have the hyperactive-impulsive type who may feel like they've a motor inside, always be on the go, find it hard to relax, find it hard to stay in a queue, interrupt others without meaning to, consistently fiddle and be fidgety. However, there's also the inattentive type (used to be called ADD but this is no longer diagnosed) where someone may zone out, procrastinate, flit between tasks, become bored easily, be distracted by noise/movement around them, find it hard to manage their time and belongings. This type can go under the radar yet it really impacts daily life. Some people may have both types (known as 'combined'). For ADHD to be a possibility, there must be challenges in at least two settings such as home and school/in the workplace and date back to childhood...although some adults will outgrow the hyperactive-impulsive symptoms.