It seems to me that the people who become successful writers are the people who make the time to write. This sounds obvious of course, but it seems to be one thing that most writers talk about. Write every day and make the time to write. I have had many conversations with people who have expressed a desire to write, but have cited lack of time as a reason not to do it.
A previous associate editor for Marvel Comics, Andy Schmidt, who now owns Comics Experience (http://comicsexperience.com/), a company that teaches people how to create comics, gave the advice that you must find time. When talking on iFanboy's Make Comics Podcast (http://ifanboy.com/podcasts/making-comics-podcast-1-start-writing/) he said that you must work out what is important to you and what can be sacrificed. If watching two hours of television each evening is more important than writing, then maybe you're not meant to be a writer.
Another piece of advice that I usually hear, and try to stick to, is that you must write every day. The brain, like any muscle, needs to be trained through repetition. Having a daily scheduled time forces me to sit down and write. Sometimes my inspiration needs a bit of encouragement and this time is perfect for doing just that.
Speaking to Author Barry Nugent (http://unseenshadows.com/contact-the-author/) at the London Super Comic Convention in February of this year, I asked him where he finds the time. Like myself, Barry has had to write his novel, Fallen Heroes, around full time work commitments. Andy Schmidt gave the advice of talking to people who were a step or two ahead of yourself because the experience that they have had, which is relevant to you, is much more fresh in their mind. With Fallen Heroes being Barry's first novel, I found his response very helpful. He explained that he would get up in the early hours of the morning and write then. That way, when his girlfriend was awake, they could spend time together without him being locked away.
Taking this advice on board, I have started getting up at five in the morning, and strangely enough, feeling excited when my alarm goes off. That is definitely a first for me. Previously, I was writing at my least productive time of day, the evening. As a result, I find I am much more prolific with my output, and an hour in the morning is worth several in the evening. For some, the evening is the best time to write and finding the time that suits you best is important.
However, with the demands of having a twenty-month old son, a full time job that goes through both sociable and unsociable hours, and trying to be a good partner to my girlfriend, I still feel that until I can earn enough money from writing to cut back on my work, some aspect of my life will bear the brunt of me chasing my dreams.
I remember a story about Stephen King working long days and then sitting at a typewriter in his utility room in the evening. He would hammer out work until the early hours of the morning, using his tumble drier for a desk. I cling onto this story when I feel like stopping. It gives me hope.