I am constantly hearing clients struggling to find space in their diaries months ahead and a consistent refrain of 'I will work on that during the weekend'.

So here is a question for you - what is your calendar/diary for? Have a look through your next three months. What does it tell you? If your answer is ‘for arranging meetings’ - and of course for most of us our diary is full of meetings - then that may be the source of a lot of your tribulations. Do you rule your calendar or does it rule you?

Lets start by trying to change the tyrannical mental model we have about that ubiquitous Outlook, Google or Apple calendar being for scheduling 'meetings'. Try thinking of it like this:

Your diary/calendar is for scheduling your life - personal and for work. Not for scheduling meetings.

Lets pretend for a moment that there is no such thing as a ‘meeting’. There is only work you do on your own priorities sometimes with others to help you and work you do with others to help them with their priorities.

Lets set ourselves some rules

You are going to avoid as far as possible scheduling a 'meeting' or accepting an invitation to a 'meeting' - you are only ever going to ‘work together on…’.
When asking others to join you to work on a task you are always going to be specific about what value you are asking them to add to the session - and when someone else asks you to join them at a ‘meeting’ then you will always ask them to be specific about what value they are expecting you to add to the session.
Never schedule work into your time-off - that is an oxymoron.
All sessions where you are working with others will start on time and finish on time. Arriving late is a gross discourtesy to the host and overrunning is a gross discourtesy by the host. Which leads to:
How does it look if you rush into a meeting directly from another meeting ill-prepared and take 10 minutes to settle in? How does it look if you rush out of a meeting with someone on the way to your next meeting without taking time to reflect and process? How does it feel if you have no time between meetings to pause, reflect on the prior session and gather yourself and prepare for the next session. So no back to back meetings - ever. You should ensure that there is a minimum of 15 minutes between meetings and 30 after or before longer sessions not including any travel time (except perhaps on a train when you can use the time effectively). Make this a clear instruction to yourself and your admin support. You can start by shaving at least 10 minutes off the finish time of meetings you have already set up.
Can you use technology more appropriately - Skype for Business, Webex etc to avoid the time and cost of travel?

The steps in managing your calendar rather than vice versa

Schedule your key personal moments - holidays, school plays and sports days, anniversaries. They are sacrosanct and what make you a rounded sane person. It is also about setting an example to those around you. Overwriting these is a cardinal sin. Only in the case of disaster do you overwrite these with work. Anything else is just telling you are unable to manage your time and tasks effectively and/or you are unable to delegate (probably because you have not spent enough time selecting and developing the people you work with).
Schedule a personal rhythm of work - meetings with yourself. Start with the twice daily fixed 1 hour slots to do your emails, convert the emails that need follow-up to tasks or delegated tasks, review and prioritise your task lists and schedule your tasks for the next 14 days into your diary - giving yourself a minimum of an hour for a group of tasks (do not scatter gun them around the edges of meetings - you are only productive when you focus on the tasks in hand for a sensible period of time).
Schedule in the time to work on your own projects - the 'meetings with yourself' where you need to devote a substantial chunk of time to think, brainstorm, write or review. Again these should be a minimum of an uninterrupted hour. Not, I repeat not, at weekends or evenings when you should be with your other half or doing stuff that makes you a balanced person.
If you want someone to join you to help you on one of your projects or tasks - then you can find a slot to schedule in the people you want to help you with your project/task. Avoid using the word 'meeting' - try something like ‘work on redesign project principles together’. Be specific about what value you want the others to bring to the session. If you cannot be specific about what you need from them then do not ask them. Never, never - 'Meeting to…’
Next - accept invitations if appropriate and relevant from anybody who wants you to come to work on a project/task with them and where they can define what they need from you. If necessary always ask ‘ what is the value that you think I can add to this session? Let your team and peers know that you will give priority to invitations that are specific about the task and your requested contribution. If it includes the word ‘meeting’ it will go to the bottom of the pile.
And finally - meeting invitations from the uninitiated! You will ask yourself very carefully what value you think you can add or you might get from these requests. And remember - attendance in itself is not adding value - it is wasting your time.

This might all seem a little drastic - but you should get the principles. Think about it. Run your own small PDSA test cycle for the next two weeks. What is the outcome?

Time to make your time your own.