Is there something that makes you more likely to do things? Try to exploit that somehow. For example, I am more likely to start doing things when it feels to me like a competition. So I think about someone else doing something similar to what I want to do, and then think: "well, I could make it even better."

This sounds more like low expectancy than lack of impulse. Impulse can make you jump off your feet to do something you want to do, but it can just as quickly distract you from doing what you want to do. Check this out. Perhaps what you might need is to increase optimism and not impulsiveness. As for the desire of doing something, try to convince yourself that it doesn't need to be perfectly thought out before doing it. For example, if you are starting a business you could be bogged down by trying to perfectly plan everything out and end up doing nothing. Instead give yourself 24 hours to start a business. Its an unreasonable request, but you would be surprised at how far you can get.