"You will never reach your destination if you stop and throw stones at every dog that barks."
-SIR Winston Churchill
Our attention is one of our highest commodities we have. What you are focusing on has a better chance of growing.
If you decide to start a business, I advise you focus on one business at a time and allow it to grow enough before you venture into another. I know a lot of people who are running three to five businesses at a time; they have one in construction; branding; and catering. The problem is, you can only give each business that much of your undivided attention at a time. Growing a business is about building systems, and systems are different in each sector. The enemy of focus is a distraction. Distractions are a part of any journey, and they are there to delay you or lower your chances of success and ultimately take you off track of your goal.
Every day we fight against distractions- if you plan to call potential clients, you will be shocked at how many other "more important things" come up. When you decide to study your phone starts beeping non-stop, or when you decide to pursue a business in a certain sector then someone alerts you to opportunities in different sectors.
The point is you cannot do everything, so divide on what is important and make sure by all means that you focus and give it you're all. Remember, every successful person had to say "NO" to distractions.