How to fill the Mind with good Positive Thoughts ?

Disciple : How to avoid Negative Thoughts from coming in our mind ? 
Happy Zen : If a land is empty, what will happen ? 
Disciple : Weeds will grow in that land. 
Happy Zen : Good. How to avoid weeds from growing in an empty land ? 
Disciple : It is not possible to avoid weeds from growing. 
Happy Zen : No. It is possible. Cultivate the empty land with beautiful flowering plants, sothat there is no room for Weeds to grow. 
Disciple : Super. 
Happy Zen : If you fill the mind with beautiful positive thoughts, then there won't be any space for the Negative thoughts. 
Disciple : How to fill the Mind with positive thoughts ? 
Happy Zen : Affirm "I am healthy, I am Happy, I am Calm, I am relaxed, I am Successful" contnuosly as much as possible. 
Disciple : O.K. Is there anything else I can do to fill the mind ? 
Happy Zen : Yes. Inaddition to the affirmations, you can also use Mantras like "Ohm Namashivaya", "Ohm Namo Narayanaya", "Ohm Namo Bhagavate Vasudevaya", "Ohm Mani Badme Hum", etc 
Disciple : What will happen when we chant the mantras ? 
Happy Zen : Every mantra is a Vibration and it will help to create a Positive Vibrations in the Sub concious Mind. 
Disciple : It is clear now. Thank you very much for your great wisdom. 
Happy Zen : God bless you God Bless Everyone