Although there is no substitute for doing guided meditation in the presence of a guru or a master, it is quite often not possible to find an accomplished teacher in your close vicinity. The other alternative is to watch the videos or listen to audios of the guided meditation prepared by the realized masters.
Guided meditation means that the teacher guides your thought process, which you follow like listening to your teachers in your schools and colleges.
While the meditation teacher is speaking, he is, in fact, taking you along on a journey of a whole new beautiful and blissful world, which is altogether different from this world. Although he may build up and correlate his theme of meditation on this world, he may suggest a line of refreshing and powerful thought process. The effect of meditation guided by a realized master will appear like a fresh, pure and blissful lotus emerging out of slush and mud of negative thoughts and mundane tensions.
The language may start in first person:
I am a spiritual being.
These or similar positive affirmations are repeated almost on daily basis till they become an integral part of our thought process.