/When we've been in school all day with unaspiring people and we're in an undivine mood, how can we get rid of this mood in order to meditate well?/
Try to think that there are two rooms before you. During the day, when you were with unaspiring people, you were in the unlit room. While you were there, feel that you were caught by some hooligans who were trying to strangle you. They were trying to take away your life-your life of aspiration.
Then, when you sit down to meditate, feel that you have now escaped from that world of destruction. You could have been killed by those forces, but you have escaped into the room of peace, light and delight, which is your true home. When you have that kind of feeling, great relief and gratitude enters into you, and your existence is automatically separated from the world of unreality.
If you do not separate yourself from this world of destruction when you come to meditate, these unaspiring forces will also come. You will carry the vibration, atmosphere and thoughts from that world in your mind. It is as though somebody has thrown a heavy load onto you. You don't know who has thrown it; you are just carrying the load. So as soon as you enter into the other room, just throw the heavy bags away.
Some people take meditation as part of their schedule. They feel that one thing follows another in a continuous series: at eight o'clock they go to the office; at five o'clock they come back; at six o'clock they meditate. But it is wrong to take meditation as just another obligation. Do not unite the uninspiring incidents in your life with the fulfilling incidents. Just separate them and give importance where it is due. When you enter into the meditation room, feel that now you are entering into the real life, whereas previously you were living the unreal life. The moment you do this, you will see that the real life is welcoming you with all its inner wealth.