I like to think I'm a productive fellow. I write open source software, build a SaaS product, mentor startups and engage in various other activities - and still make plenty of time to cook my girlfriend a lovely dinner on most days. How does one person manage all this? Read on...
1) Do what you love
Personal motivation plays a huge part in productivity. If you aren't doing a job you're passionate about you have no hope of being productive at it. Figure this part out first and the rest is a lot easier.
2) To-do sessions, not days
I never write a to-do list for a day. So many things can happen in a day to distract you outside of your control - a colleague wants to meet, you have to run an urgent errand etc. The best solution I've found is to think of to-dos in terms of sit-down sessions rather than full days. Sit down at your computer and write out the to-dos you intend to accomplish in that session whether it's one hour or two hours. Then take a break and go do something else. Then repeat.
I don't mean from the internet, I mean from work. Taking a day off every week is as important as being productive for the rest of it. Your brain needs time to empty, you'll gain insights while your mind is at rest and you'll prolong your passion for the work.
4) Get up early
My life pretty much transformed as soon as I started getting up early in the morning and working almost straight away. I wake up at 7, have breakfast and am usually finished with the things I wanted to get done that day by noon. That leaves the rest of the day to get a head start on the rest of the week's tasks or simply to let my mind rest and perform some "soft" task such as brainstorming.
5) Timing is everything
...that said, everyone has a different time of day when they are most productive. For me that's the morning. For you it might be different. Learn what that time is and capitalize on it every day. Don't waste it.
6) Learn to say No
I often get asked to participate in things. Conferences, business lunches, consulting offers. If you feel it will be a distraction, you have to learn to say no. If you get a high volume of requests and can only say yes to a few things, figure out what your selection criteria is and stick to it - it will make decision-making a lot more efficient.
7) Talk to your customers
One activity that instantly fills me with both motivation and inspiration is talking to customers. They don't even have to be your customers yet - even talking to potential customers is hands-down one of the most productive uses of your time if you're running a startup.
8) Set crazy goals and achieve them
There's nothing better for productivity than setting some huge goal, a deadline for it, then working towards that deadline. In a startup situation this is easy - release big iterations of your product or service (1.0, 2.0, 3.0 etc) one every couple of months with a features and design update, each time doing customer development to figure out what the next version needs added or taken away.
9) Meetings with purpose and outcome
Meetings are poison to startups and often eat into everyone's productivity. You can run meetings successfully by making sure that everyone knows what the purpose of the meetings is, what the outcome should be, and what materials they need to prepare before attending - and sticking to a strict time slot. My number one pet hate is vague meetings such as "just getting everyone on the same page" - that kind of thing can be done via email. A meeting is a mechanism for deciding something concrete. Some startups like to have weekly or daily meetings where they look at metrics - that's fine, but don't sit there staring at numbers and nodding, use the meeting to decide a course of action based on the metrics.
10) Put your damn phone away!
The last one in my list but both brutally simple and effective. Some people say you need to disconnect from the internet to be productive but I never find that a problem - and in fact as a programmer that's probably counter-productive as I'm so often on stackoverflow looking up some solution to a problem. What I do find helps my productivity is disconnecting from the mobile world. There's nothing more distracting than getting texts, email notifications, candy crush invites etc etc flashing up in the corner of your eye while working. Simply turn your phone over while in the zone, or put it in your pocket. Easy.