Daya is already inside of everyone, as it is put in by God. All it needs is evoking and somebody to light it, to bring it out of us. But the only way we can inspire somebody towards that process is if we're acting out of Daya. We must act out of absolute unconditional love. Then that Daya will run over to them if they allow and open their hearts to receive it.
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Sometimes our Karams (actions) are so strong that we are not able to allow anything in and it takes little extra effort on our part. Some people have to work harder because of their big load of past actions. Since they’re carrying such a load from their past, it will take that extra effort to help them break that down. We can take steps of doing the traditional Seva (selfless service) that Guru has given us such as waving a fan over the Sangat (congregation) during hot weather and washing utensils in Langar (free communal kitchen). Such Seva will help us evoke Daya that’s already within us.
To learn more on this topic, watch the video by Bhai Baljit Singh