I was diagnosed hyperactive when I was 7 (1985) which was quite early to be diagnosed in this country, particularly by an old fashioned doctor as our family GP was. My mother was greatly relieved by this, since she had been convinced that her parenting skills (which were fabulous) were not up to the job and that it was her fault that I was 'misbehaving' in the way that I was.
I didn't have it too badly, but was prone to 'episodes' the results of which I wouldn't remember (rather like when some people are drunk). The doctor didn't really suggest much in the way of treatment, but said I would grow out of it.
The doctor was wrong. I still have a low concentration span, poor spatial awareness, poor co-ordination, a tendency to insomnia etc When I was first diagnosed, a family friend suggested avoiding E numbers 100 - 180 and 200 - 290 which helped significantly. I still try to avoid additives, although they don't affect me as badly. Too much cola still makes me appear drunk, though.
I developed various coping strategies. For example, at Uni when I had several essays to do, I could not do one, finish it and move on to the next. I found it much easier to have them all on the go at once and dip into each of them as I got bored.
My brother in law was hyperactive when he was a child and HAS grown out of it. However, this means that I want to keep an eye on our child and ask the doctor about any warning signs since there is a large genetic component to hyperactivity.