Depressed about my diagnosis?

I am 23 years old and live in Scotland. Ever since i left school at 18 i always suffered with up and down moods.I would have periods where i was so low and depressed i slept for days on end and didn't eat and didn't want to talk to anyone. Then there would be periods where i could stay up for days with sleepless agitation. I was extremely irritable and lashed out at those close to me over the slightest thing.My anger knew no bounds during these periods. My thoughts also raced uncontrollably, i had so much energy,I thought i was invincible, i spoke really quickly and incoherently and i believed i was a famous movie star.My family reached breaking point about 6 months ago when, during one of my high periods, i started running towards a moving train and nearly got killed.My family took me to my GP who referred me to a psychiatrist. After being evaluated for six months i was finally diagnosed with Rapid Cycling Bipolar Disorder.I am now on 1200mg of Lithium. In a way i am glad to finally have a name to my feelings.But on the other hand i am really downhearted and depressed about my diagnosis.Can i live a normal life despite the diagnosis?Thanks for reading and i would appreciate your thoughts.Take care.