1. Think of your business as a business - not a hobby. Even if you don't invest a lot of money to get started, be committed to working your business just as if you had invested over $100,000. to get started. People with hobbies quit (at least for a while) when they have bad days. People with real businesses will give the effort needed to make their business a success.
2. Think long term. If you have a bad week (or a bad month), do you quit. Successful business owners can handle the ups and downs, because they are focused on the long term reward of owning a real business.
3. Self Discipline. Do what you plan to do. If you have 20 sales calls scheduled, make all of your calls. If you have 12 follow-up letters to write, don't let yourself go to bed until they are written. Each action you accomplish takes you closer to your goals.
4. Persistence. If you never give up, it is almost impossible for you to fail. If you're not ready to push yourself ahead when you have setbacks (especially small discouragements and inconveniences), you really shouldn't even start. You can be a success, but only if you persist long enough to get past the inevitable setbacks you will run into.