It certainly can feel like some times we are just constantly wasting too much time, and that lack of managing our time causes us to use precious time we could be using for leisure time. Managing your time could be easier than you think.
To always being doing something isn't the key, although it would appear to make sense to think that way. However the fact is it isn't about always doing something but rather when ever doing something doing it with the right attitude and the order in which that you do things.
Approach your day with an eager approach to accomplish everything on your list of things to do. Sub categorize what you have to into like categories to limit the amount of transitioning that you have to do. For instance, if your are cooking a meal, start cooking the things that take the longest to cook first. When you find yourself waiting for water to boil, or something along those lines, focus on another aspect of the meal like a salad and if there is no more food preparation that needs to be done start cleaning up what you can in the kitchen. Spending 30 minutes in the kitchen will be more productive than 10 minutes in the kitchen, 10 minutes on the computer, then another 10 minutes in the kitchen to finish the meal only to later have to return for 10 more minutes for other kitchen related duties you could have done in the time you were working on your computer. By staying in the kitchen you can keep a better eye on the food anyway and won't waste any time going to and from the computer.
Usually if you write something down right away you won't forget it and you'll save time not trying to remember what it was you wished you had written down, having a master notebook for all notes will really save you time and space. Rather than taking inventory every time you go to the grocery store keep a pad on your refrigerator and write down something the second you are out of it or have a low enough amount of it that you need to get more. Then as you walk out the door grab the list. When you make a list of things to get at the grocery store another time saver is to list foods in their subcategories like dairy, produce, frozen and dry foods, which you of course could sub categorize as well. You can easily do this by taking a few seconds to write the categories on the pad. Don't waste time looking for a pen and pad, use a magnetic to hold up the pad and tie and pen to the pad.
Lastly use multitasking appropriately. Try doing two things, one right after the other, two things that if you had to you could do them at the same time. Remember the time that it took your to complete both tasks. Then do them together and see if it takes you longer or if you finish in a shorter amount of time. Somethings are just not made to be done at the same time, this will help you discover which ones they are.
Multitasking can be a good approach to saving time or bad approach to time management if the things you are trying to multitask at are not compatible.