Having a busy schedule, working for your day job for at least 12 hours, and you still need to be motivated to hit the gym as you have a body building competition two months from now. Staying motivated will be very tough. Just like on the video on this article, Arnold Schwarzenegger kept on moving on with his workout even with busy schedules, he kept his focus on his goal.
So what are the steps that you can try to stay motivated? First, start with a workout that is realistic and that it fits with your schedule. Maybe start with a workout that only lasts for 20 or 30 minutes until you become comfortable with it and you can add more hours to your workout. Another step to follow to keep yourself motivated is to get quick and initial results. Before you start any workout or program, make sure that you have weighed yourself, so that when you get the results, you will be motivated to do more.
Another step on keeping yourself motivated is to read and watch motivational articles or videos such as an example below, will help you to think big, to set your goals and keep your focus on what you want to achieve. Always think about why you started it, and never look on the side of quitting.