When you go through your day, what are you thinking? I know this sounds like a weird question but you really need to answer this for yourself. You talk to yourself (maybe not out loud but thinking is talking with yourself) more then you talk to anybody else in a day. It is important how you talk with yourself.
Think about your thoughts during the day. Are they negative thoughts? Negative thoughts can be very destructive to your life. I know it doesn't seem like it would matter but it really does. Think about it for a minute. On the days that you had more negative thoughts, how were the results of various things in your life then? I am sure the results were negative. Negative thoughts lead to negative results.
Your thoughts have a bigger affect on your results then anybody or anything else that you come into contact with. Thoughts set up your attitude towards things you are doing. If you think you will not succeed, you will be setting yourself up to fail. You will not be motivated to do your best and you will not believe in yourself.
Now let's turn that around. Think about positive thoughts. If you think successful thoughts and think about things you can do, you will be in a positive mood. You will then be motivated to push yourself to succeed. This goes for anything in life, not just business. Try it out, I am sure you will see the difference!