In this excerpt from Kopan Course No. 27 in 1994, Rinpoche explains that if the cause is not created, the result cannot be experienced.
A strong understanding of karma gives energy to the mind and increases the fear of creating negative karma
When we practice thought training, experiencing problems becomes a cause for finishing the results of negative karma
To eliminate suffering and obtain happiness, the most important thing is to have a good heart
Teachings on karma, excerpted from a lam-rim course led by Kyabje Lama Zopa Rinpoche at Maitreya Instituut, Emst, in August 1990.
The karmic results of nonvirtuous actions are experienced in this life or in future lives, unless we purify the negative karma.
Excerpt from an edited compilation of Rinpoche's teachings on the subject of karma.