Too much work; too little time. We all struggle with this issue. Downloading a hundred time management apps won't help. True productivity requires discipline and having a robust mental routine. Here's what helps me.

1. Triage

You can divide your work into three categories: the big stuff that counts, makes a difference and makes money; the small stuff which is fundamentally administration; and the other stuff that, left alone, will disappear. Ignore the last, separate the first two, and do the big stuff first. Leave the administration until after 4pm when you're less fresh. That means your best mental energy is devoted to the work that makes an impact. It also gives you a boost at the end of the day because the small things get done quickly, so you leave the office with a sense of accomplishment.
Don't mix the two types of work. Multi-tasking doesn't work; it's exhausting and impedes your ability to do real thinking. It's also favored by people who are impulsive and over-confident, hardly an advertisement for an inefficient way of working.

2. Limit Meetings

Try to keep meetings confined to afternoons and to do no more than two in a day. Just because you have "free" time in the calendar doesn't mean you have to fill it up. Unless it's a major strategic review, never accept a meeting exceeding two hours; no one can stay focused for longer. And don't attend any meeting that doesn't have a finish time.

3. Build Healthy Habits

When you adopt a routine, you build neural networks in your brain that process information and decisions faster. That's why routines feel easier the more you stick to them. I have two separate routines for the office and for being on the road. Limiting my choices frees me up to spend mental energy on things that matter more. At the office, I start on time, finish on time and don't stop for lunch until I'm hungry. On the road, I always eat before boarding a plane and on the plane, I always sleep. On short flights, it's a boost and on long-haul flights it's essential.

4. Sleep

Losing one night's sleep is cognitively equivalent to being over the alcohol limit--without any of the mood enhancement of a good cocktail. Don't be heroic. Get at least seven hours of sleep every night and if your schedule won't allow that, catch up in the day time. Think of this as asset integrity: maintaining the structural soundness of your equipment so that it won't break. Every high achiever I've ever known takes sleep seriously.
What are your essential tips for productivity?