Absent-mindedness can be cured only by being mindful of everything from moment to moment. You must "live in the present". You must be aware of the happenings, you must be conscious of the happenings, at every moment. In due course of time, you will be conscious of each happening from the time of your awakening in the morning till the moment you fall asleep.
This awareness of every moment can be cultivated gradually till you are no more ever absent-minded. Try it for 5 minutes at first and then gradually extend the time. You will be living every moment for the first time in your life, and you will discover how interesting it really is.
Here are a few exercises:
Exercise 1. Basic Awareness
Be aware of your breathing in, and breathing out. Be conscious of your breathing through the nostrils, through the nose, "In" and "Out". Let your breathing be natural. Do not force the breathing.
This is to be your basic awareness throughout your waking hours. You must go back to this basic awareness of breathing in and breathing out as soon as you have finished being aware of whatever particular thing you have been doing, i.e. your daily chores or your daily work.
Exercise 2. Walking
Be aware of every movement of your legs. Let us say that you start walking with your left foot. First be aware of your intention to walk. Next, be aware that you move your left leg forward, then be aware that you move your right leg forward, and so on. You are aware of your walking, left, right, left, right.
Now walking more slowly, be aware of your movement of each leg in two sections or parts. Be aware of your left leg going forward and your putting it on the ground. Then be aware of the right leg going forward and your putting it on the ground.
As you improve in course of time, be aware of the movements of each leg in 3 sections or parts. Be aware of the leg being lifted from the ground, then moving forward, and then your putting it on the ground.
In any spare moment between the awareness of the movements of your legs, go back to the basic awareness of breathing in and breathing out.
Exercise 3. When you want to sit down on a chair
Be aware of your intention to sit down; think very quickly, "I want to sit down". Be aware of your first movement towards sitting down. When you have sat down, think very quickly, "have sat down".
Then go back to your basic awareness of breathing in and breathing out, till you want to do something else.
Exercise 4. When you want to get up
Be aware of your intention to get up; think very quickly, "Want to get up". Be aware of each movement towards getting up. When you are up, think very quickly, "I am up".
Before you intend doing something else go back to your basic awareness of breathing in and breathing out.
Exercise 5. When you want to drink
Be aware of your intention to drink. Then be aware of your extending your hand towards the cup, be aware of pouring the water in the cup, be aware of lifting the cup towards your lips, be aware of each successive step right up to swallowing the water, be aware of putting down the cup, etc., till the act of drinking is over.
Then go back to your basic awareness of breathing in and breathing out.
Exercise 6. Eating
Be aware at every moment of every movement towards eating, be aware of using the fork and the knife or the spoon, of every successive movement of drinking your soup, of each successive movement of cutting your meat and putting it in your mouth and chewing and swallowing and the return movements of your hands towards your plate, and so on.
In-between, go back to your basic awareness of in and out breaths.
Exercise 7. Lying down
You must always be aware of your intention to do anything: in this instance, lying down. Think very quickly, "want to lie down". Then be aware of every successive movement.
Exercise 8. The Sensations
Whatever be your physical posture, whether sitting or standing or lying down, try to be aware of your various sensations. Say you are sitting. As you sit, you will want to move your position. Think quickly "want to move". Then be aware of your movement whatever it be.
You may feel itchy. Be aware of your itchiness. Think to yourself- "I am feeling itchy". Concentrate your mind on the itchiness. Usually, the sensation will gradually disappear as you concentrate and improve your concentration. If the sensation gets worse, you may wish to scratch: If so, think to your self, "I am going to scratch".
Then be aware of moving your hand towards the spot, be aware of your scratching and be aware of the disappearance of the itchiness, and be aware that you have stopped scratching and that you have withdrawn your hand.
You may feel a pain. Be aware of the sensation of pain. Think to yourself, "I feel a sensation of pain. Then concentrate on the pain and make a suggestion to yourself that it is disappearing and usually it will disappear. If the pain gets worse, you may prefer to change your posture to get rid of the pain. Think to yourself, "I want to change my posture". Then change it and be aware of it.
You may feel tired. One of your limbs may feel numb. There are all sorts of other sensations of your physical body. Be aware of the sensation, be aware of your intention to do something to overcome or change the sensation, and be aware of what you do.
And always in the meantime, go back to the basic awareness of breathing in and breathing out.
Exercise 9. The five senses
When you see, be aware and think to yourself, "I see". Then go back to your basic awareness of breathing in and breathing out. Or you may wish to go on to see something else. Just be aware of whatever you are doing.
When you hear, when you taste, when you touch, when you smell, be aware and think to yourself of whatever the sensation is. Be aware, be conscious of whatever it is.
Later go back to your basic awareness of the in- and out-breaths.
Exercise 10. Your thoughts
Be aware of your thoughts. As your mind wanders, think to yourself, "wandering". As your mind dwells at a certain spot, think to yourself, "dwelling". If you meet a friend in your thoughts, in your imagination, think to yourself, "meeting". And so on. Then you let your imagination run riot. Be aware of every successive run of your mind. Later consciously bring your mind back and be aware of it. Be aware of every successive movement. Then bring it back to your basic in and out breathing.
Exercise 11. On reading
Be aware of your intention to read. Be aware of the opening of the book, your starting to read, and in the marginal zone of your consciousness, be aware that you are reading.
Be aware, Be aware. Be aware when you are feeling tired of reading. Be aware when you wish to stop reading. Be aware of your stoppage of the reading.
Exercise 12. On awakening
As soon as you awake, you should be conscious immediately that you are awake. This will not be easy at first. Before you go to sleep at night, suggest to yourself that you will be aware of the fact of your awakening as soon as you awake. Suggest to yourself every night before you fall asleep.
After your first moment of awareness, continue being aware of every other happening, of your movements in getting up, of your ablutions, of your walking here and there, to and fro, of your sitting down, etc. In other words, be aware of every consequential act, of taking your meals, of going to work, of your work itself and the 101 things connected with your work and your movements in their connection, etc.
Always, in the meantime, be aware of your basic breathing in and breathing out.
The above are a few exercises to show you the way. You can realise the immensity of the subject. Be industrious.
Try for 5 minutes at first. Then extend the time. In the end you will be aware of everything from the time you wake up till the time you fall off to sleep.
Day by day and week by week and month by month, you will improve. There will come a time when you can never ever be absent-minded again.