I wrote these words today to a Dharma friend who was sad that he is not able to teach or help those who live far from him. I hope you guys will also find it useful: 

Being an example of faith is teaching without words. If you are established in faith others will be helped just by being in your presence because they make a karmic connection with a future Buddha. It is the same with the people you met and you could not help. Even those you didn’t meet but you think of them, will receive your help after you become a Buddha in the Pure Land. This is because you create a karmic connection with them by keeping them in your mind. 

If you have faith (shinjin) you automatically help visible and invisible beings even without teaching them directly. Invisible beings are helped just by knowing your thoughts of devotion towards Amida and by hearing you saying His Name. Also huma