There is a way to develop internal motivation - in my opinion it is one part the realisation that you want to be motivated and the other part putting in the hard yards to build habits. For the first part I always refer to the concept of the elephant driver as a reminder.

"NYU psychologist Jonathan Haidt uses a lovely analogy to explain both: the emotional side is the elephant, the rational side is the rider. The rider of the elephant looks like he or she is in charge, but when there’s a disagreement between the elephant and the rider, the elephant usually wins.

Chip and Dan Heath's superb book, Switch: How to Change Things When Change Is Hard, builds on this analogy and talks about directing the rider (rational brain: responsible for planning and direction, but can get paralyzed overthinking things) and motivating the elephant (emotional brain: prefers quick gratification over long term, but gets things done). Numerous experiments show that the rider can get exhausted trying to motivate the elephant and needs time to recover. This is why, if you’re trying to eat healthily while on the road, you tend to make bad choices at the end of a long day and opt for that extra glass of beer."

For the second part use mobile apps/smart watch to help you build habits. Being an unashamed apple user I rely on streaks to be my habit builder but there are many similar applicatons out there. Gamify your own life. Because at the end of the day life is a game. And if you want to get to the next level you have to play it.