I'm a really visual person and so I motivate myself by keeping a computer log of my body compostion (fat, muscle, water, weight), BMI and different types of activity on different graphs on a spreadsheet. Whenever I weigh myself i put the data in there as well as here and I can see how I'm doing.
When I look at other people who seem to find fitness easy I remind myself that they are just the same as me and not superhuman.
The only difference between me and them is that they have already made fitness a habit.
When something's habitual you don't have to think about it, it just happ...