Keeping yourself focused and centered on a goal you want to achieve has two levels, and they're both very important to succeed.
The first level to focus is simply doing. Try not to delay or putting off things to do “later” and get distractions out of the way, if not... you won't never get them done.
The second level to focus is to be sure you're doing the right things – set up priorities, with clear goals, that have an external impact for you and your business.
what are you doing right now?
why are you doing it?
what results are you expecting from it?
what should you be doing instead?
For the last month I've been very focused on my goal. When I'm not working on a customer's project, I've been working on my own website's upgrade. Many new graphics have to be created, many new module installations, and code twists to make it work as I want it to. Without leaving behind all the other matters of the business and customer's jobs that have to done.
You can set yourself some goal daily, weekly, monthly and yearly. That way you can focus your everyday priorities that all together will end on the accomplishment of your yearly goals. Doing little by little you don't overwhelm yourself and you can see how every single and simple task helps in growing your business and your own personal life.