I went through life without knowing I had ADHD, and I did just fine. I graduated from college in 2008 without any official diagnosis of ADHD, although it was a running joke with my friends and family that I had ADD. This was due to my wide (very wide) variety of interests and hobbies, as well as my ability to quickly switch my focus (some call it being "distracted").

Once I switched from menial retail jobs to full-blown cube-jockey (working in an office) it was apparent I could not keep my full, un-divided attention on my work, even if my job depended on it.

I decided it was time I sought professional help.

I still struggle with paying attention at work, but I found an employer that is lenient with the things I struggle most with; I struggle most with being on-time and being 100% focused on work 100% of the time.

Now, I'm not so sure I consider my ADHD symptoms are a hindrance to my life. Oh my symptoms definitely still cause problems (finding my car keys, going to bed on-time, finishing anything), but more than those minor issues cause me grief, I've found that much of my charm and character come from those "troublesome" symptoms:

My many, seemingly-unrelated, interests just means I'm never bored; I have a huge inventory of experiences and talents I've learned, and I have a beautiful variety of friends whom I cherish.

Because of my forgetfulness, I became a diligent note-taker and collector of information. I suspect this lead me to my current career as a Technical Writer (I know, sounds like hell for someone with ADHD, but I manage). 

Even though I jump from project to project (to project to project), because of my coping mechanisms (above bullet), I've managed to build some pretty amazing things and accomplish things (concurrently) that most people literally could not even dream of.

"I have many talents and many interests. To ignore any would deny myself an opportunity to find out who I am or where I come from, or miss something extraordinary.

If it is interesting, I will explore it; I am a collector of beauty and wonder.
I cannot live any other way."

-Me, in response to the suggestion I might have "too many interest," and perhaps I should "narrow it down."