Assalamu Alaikkum wa rahamatullahi wabarakatuhu,
Time is all we have, and you may find one day, you have less than you think. This is quote by a Professor who died of cancer in very young age and he is famous accomplishing many things in the academia and for inspiring many students. Of course, managing time wisely is the most important thing for almost everyone. Everyone wants to get more things done in less time. My professor often asks me why I rush through everything and why not take a break. I tell him Asians don't have a high life expectancy and I have lot to do before I die.
The way I try to manage time is by classifying things, prioritizing them and planning them. Though I don't have much control on how events would unfold everyday, the minimum I can do is to have a plan. So, I prioritize my work based on due date, importance etc. And I try to work according to the plan though it might shift a little from it. And the most important thing is to make it a habit.
The next important thing is to have a "healthy" mind, "healthy" surrounding and a "healthy" biological cycle. By "healthy" mind, I mean try not to think about something else while working on something. Forget everything for the moment, and work on it. Because, lack of concentration on what you are doing right now, will make the time taken to get it done longer. By "healthy" surrounding, I mean have your desk organized. Even if it takes lot of time to get it organized, believe me, it is worth it. Because, most of the times, we spend our time searching for something. Have your desk, room and everything organized. By "healthy" biological cycle, I mean especially sleep, no matter what happens in the rest of the world, I go to sleep early, so that I can wake up for Fajr. Never disturb the sleep cycle. Then the whole of next day is ruined.
Alot time for every single thing in your plan. Even for time in TTI. I distribute around half an hour for TTI every week day. When the time is up, quit it, no matter what. It might be cruel thing to do to yourself but that is how I learnt it. Sometimes we have to be cruel on ourselves for our benefit. So, have a limit for everything. A balance. There are people who start studying the deen and completely neglect their school and there are some who get occupied with school and dunya and completely neglect the deen. Don't be any of them. We always take the middle path, the balanced one. Never overdo anything.
Classify things as value added and non-value added in your life. Value added are those which add something more to your knowledge, comfort, happiness, family and Imaan. Non-value added are the rest. Try to reduce the non-value added things. When I started this approach, I got rid of many things like facebook etc and I got lot of valuable time back for other things. You might feel sad intially for getting rid of these things but later you will not miss them.
One last thing, no matter what, holiday or weekday or vacation, try to keep yourself busy with something. This will prevent Shaytan to take control of your mind.
I am probably not old enough to advice anyone. But, these are the things I learnt the hard way. This approach has helped me to stay sane and manage my time. I hope it is of some use to you. Jazaaki allahu khairan for bringing this topic up.
Wassalamu Alaikkum.