Self-management is a familiar idea to anyone who has got somewhere. It is one of the things that decides how much value and how much output you are actually capable of producing. Here is what it means in practice and how to work on it.
Why self-management matters
When people talk about the art of management, they mean the flexibility and judgement involved in applying methods, tools and principles to get work done as well as possible. It gets measured in economic results.
Self-management is simply that same art turned on yourself. People often ask why they should manage themselves at all, and what it is supposed to achieve. In practice it is simple: if you want to be in control of a situation or a piece of work, the first thing you have to control is yourself.
One philosopher put it as: the greatest victory is the victory over yourself. Once you have that, no matter how hard the task is, you can carry it through. And it has to be maintained, not achieved once, because as the old line goes, sow an action and you reap a habit, sow a habit and you reap a character, sow a character and you reap a destiny.
How to actually practise it
It is called an art because it depends almost entirely on your own initiative. People who never get a grip on it tend to fail repeatedly and lose heart easily. Here is what works.
Build the habit of taking responsibility
The first habit to build is being willing to own outcomes. For any problem or task you are responsible for, you commit to it fully. And if it fails, or falls short of what was expected, you are the first person to stand up and account for it.
A lot of people default to blaming others or blaming circumstances when things do not get done. Over time that habit hardens into something worse: self-interest, a reflex for excuses, an unwillingness to do the work. At that point self-management has already failed.

Think with some maturity
“Everyone grows up eventually” is a line most of us have heard many times. But that kind of growth is not decided by age or by years lived, it is decided by experience. Someone who thinks maturely is someone who has learned to manage themselves.
To get there, learning and accumulating real experience matters far more than anything else. For example, when your manager hands you a task, instead of sitting at your desk reading books and searching the internet, go out, talk to people, spend time in the actual environment. That practical knowledge is what makes the difference in the result.
Put the important things first
There will always be big tasks and small tasks, and someone who manages themselves well puts the important ones first. Work out what has to be finished first and what can wait, then build a concrete plan around that.
While you are planning, build in some slack. There will always be side work that needs doing alongside the priority items.

Assess yourself honestly
Self-assessment is a core part of this. It is how you look at yourself clearly, review what happened, and understand yourself a bit better. Do it against a concrete plan, weekly or monthly.
And do it honestly and objectively. When you got something wrong, say so plainly to yourself and be strict about it. A self-assessment that never finds anything wrong is not an assessment.
None of this is complicated. It is just consistent, and consistency is the part most people skip.