Change your physiology first
If you want to change the way you act, do yourself a favour and change your physiology first. It is very difficult to get up and do something that you have been putting off if you are slumped over in your chair and feeling tired or miserable.
Your physiology triggers the patterns that are activated in your mind. A sad expression and slumped body will activate the parts of your mind that know how to act depressed. A happy expression and erect posture, on the other hand, will activate the areas of your mind that function when you are happy. It will also trigger happy emotions in other people.
Think about how you would hold yourself if you were extremely successful. Would your back be straight or arched? How would you hold your chest? How would you walk? For the next ten minutes, act as though you are extremely successful.
Think about how you would hold yourself if you were extremely excited and motivated. What would you be doing with your hands and arms? How would you speak? What would your face look like? Act as though you are extremely excited and motivated for ten minutes.