How do you Motivate yourself when you have no external sources of Motivation?

I believe that inner motivation is more powerful than any other motivation that comes from an external source like an individual, movie, seminar, book etc.

Motivation that has its source 'within oneself' triumphs over external motivation as it comes from deeper understanding that carries with itself a heavy emotional strength. As an example let us consider that my family and friends suggest me to hit the gym and get in shape. Although I do understand and value the concern they have for me and it does make perfect sense too, but for some reason I do not have an inner drive or that necessary enthusiasm to reduce my weight and tone myself up. One fine day, I take a good look at a picture of myself where I stand beside my 'in-shape' office colleagues. As I look at myself carefully, I begin to realize how unattractive I look with these excess pounds. This is where I link my weight with my 'looks'. Soon after this realization, comes an inner push to do something about it & from the next day onwards I myself hitting the gym and adopting healthy eating habits.

Although, there are a number of ways one can motivate oneself. They all differ person to person as we all have different beliefs and attitudes. Let me jot down a few of them that have worked for me.

1. I do a simple but powerful exercise that involves looking at where I was a few years back (3 to 4 years back) and then compare my life at that time as to what it is today. I then write down at least 10 significant changes that I have experienced so far and also look at the ways they have affected my life (whether positively or negatively). When I realize that NO extraordinary improvement has taken place, I consider that as a wake -up call to take better quality decisions and actions 
2. Doing a quick self-analysis on whether my capabilities have been used to the fullest or have they been largely unused. This gives me clarity on my all the mental and emotional blocks of my life. This helps me understand where I am stuck. Once the root cause is detected, a strong current of self-motivation gets triggered to get rid of that root cause which is not allowing me to live my potential to the fullest. One such example can be the fear of public speaking that hinders many opportunities that I would otherwise grab if I at all had the necessary confidence in that area 
3. Death too can act as a tool for self-motivation, at least it does in my case where I tend to visualize myself on my death-bed and I am full of regrets about my unfulfilled dreams just because I was not motivated enough and always gave excuses. The moment I imagine this picture, within a few minutes I feel the rush of inner-motivation, the feel of which is strong enough for me to be at my peak performance.
4. The last tool I would like to mention is something that I rarely use. It involves comparing yourself with someone else (especially someone who is of your age or younger and who started his/her life from a similar background as yours) This may not work positively all the time as there is a risk of a subtle feeling of jealousy dominating this entire process and making it counterproductive. But on the positive side, it can act as a strong source of inner-motivation as it will make you understand all those areas where you were weak and where this 'other' person was strong. The underlying thought that one should have is -"If they/he/she can do it so can I"