Procrastination is a widespread problem. Advice on fighting it is just as varied; ultimately, you have to figure out what works for you. But I'll share five tips that have helped and stuck with me over the years:
1) Motivation = momentum. Inspiration follows action, not the other way around.
The myth is that you need to work on getting yourself "in the mood" or "find inspiration", and then it will be easy to work from there. The reality is, motivation isn't something that gets you started, it's something that keeps you going.
Next time you're thinking about browsing startup blogs for a half hour to find some inspiration, or playing a game for a bit to get yourself in the mood to work, tell yourself to work on whatever it is you're procrastinating for just five minutes. It's much easier to keep working once you've gotten started.
2) Willpower is the art of remembering what you really want.
Another reality of startups is that the work is very different from the vision. The vision is making a difference, happy customers, solving problems, making money. The work is cross-browser CSS, promoting blog posts, making sales calls, doing accounting. Most of us would rather do something else than do those things. The trick is to keep framing the choice not as "read blog posts / play games vs [boring work task]" but as "read blog posts / play games vs [accomplish vision]".
Figure out what you really want, and make it very, very, visible in your workspace. Print it out as a sign, etc.
3) Procrastination is often fear in disguise. Failure comes from inaction, not from bad results (you can improve).
If you're procrastinating, ask yourself if you're afraid of something. A lot of times we're not even conscious of why we're not doing the things we thought we wanted to do. Is it because you're afraid you can't do it? Afraid you can't do it as well as you want?
It's much easier to tell yourself you failed because you "weren't really trying" than it is to admit you just couldn't do it. And so often we hold back because we are afraid we're going to fail, and we want to soften the blow. Ask yourself if you'd rather continue to succeed at doing nothing, or continue to improve by risking failure.
4) Time management is a system, not a skill. You're not as good at it as you think you are.
Traditional jobs actually have a lot going for them. You have a firmly set blocked-off period for work. You have deadlines. You have a limited number of things you need to allocate your time to. Many startup founders have no set schedule, no real due date for individual pieces of work, and a whole set of tasks (brand-building? security? design improvement? networking?) that it's unclear when they need to be done by or how much time to spend on them.
With so much ambiguity, it's easy to think you have more time than you actually do, and easy to think you're spending more time on productive work than you actually are. Take time management seriously, as a system you need to set up and hold yourself accountable to, not as a 'skill' you're naturally good at. Create a schedule. Set deadlines.
Set some time to figure out how you should allocate your work time, and budget your time off. Add more to this budget later if you find you need it for a healthy work-life balance, but make the amount of time you're spending on non-work something you're choosing, rather than something that just happens.
5) Measurable progress is candy for the brain. Find a way to break down everything and track progress on it.
Another source of procrastination is feeling overwhelmed. There's so much to do, and sometimes it feels like you're swimming in the ocean without getting any closer to shore. Fight despair: make your brain happy by finding a way to break things down and measure your progress on them.
Got stuck on a bug and dreading going back to it? Type out what you've tried, what you need to investigate, who / where you can ask for help, phrases you can Google, etc. Strikethrough as you go. Building a web app by yourself? Become a one-woman Scrum team: create a product backlog, work in sprints on different sections, separate your to-dos from what you're doing, and keep visible what you have gotten done.
Good solo founders are good project managers. An idea, no matter how powerful, is very small -- it's easy to get excited about because we understand it completely. The reality of implementing it is vast and full of unknowns. If you want to stay interested in moving forward, keep mapping out the next portion of where you're going.