Never give up if you have a dream to produce a particular work. I was rejected many times over before I was able to publish my first book and indeed it took five years to write it and secure a publisher who understood my vision. This one took a bit less time about a year or so. But the first publisher I had secured decided after several months the book was ultimately not right for his press's audience. I felt devastated. Still I felt this was a story worth telling so I persevered to find another publisher, which thankfully took only months. It still took a year for it to come to print. Expect to do a lot of revision on your manuscript that is time consuming after its first iteration and acquire a thick skin for receiving early reader's reports. They can be a bit of a shock in their frankness, but if you look past that their is usually some very constructive things to be gleaned from them and it can definitely improve your work to be open to such criticism. Its hard to be a writer, its isolating work, many people you know may not be versed in your subject, or interested in hearing about every step you take along the way to getting to your goals, so my advice is spend time cultivating friendships with other writers who understand the process.