Keeping focus on the here and now is why mindfulness is a skill that has to be cultivated. Pushing the thoughts out and maintaining focus on what you are doing right now is key to good mindfulness.

One can share or send energy to another person, in the here and now, and be mindful. Carrying on a conversation with someone can occur also, as long as you don't allow your mind to drift while they are talking, or that you don't go reminiscing and following your thoughts to what used to be, or visualizing into the future. Keeping focus that you are "two individuals having a great conversation over coffee on a cool sunny day" for example, is what counts.