@Mirha_reads, well, I would tell you how I started. I had a story in my mind already but I never found courage to actually write it down. One day I discussed it with my friends and they appreciated the idea and helped me in deciding the names of characters. Later, that day I wrote the opening lines. So the process started. The real motivation behind all this was the main character of this novel, she always ignited me and made me complete this novel.
If you want to write a novel, write it. Start by writing a line about the story or about the character or about the weather, just write any line and you will be driven ahead. You have your own story, your own writing style, pick up your pen and get started. Don't rush your novel. It won't be completed in a day. It will consume months and years. So be patient during the process. Start and you will eventually complete it. :-) :-)