The Power of Now
I'd love for my sister to read this, I think it would help a lot if she "got it" in any meaningful way.
Two of his more important thoughts (read more here and here):
Only the present moment exists.
That is where life is (indeed it is the only place life can truly be found). Becoming aware of the 'now' has the added benefit that it will draw your attention away from your (negative) thoughts. Use mindfulness techniques to fully appreciate your surroundings and everything you are experiencing. Look and listen intently. Give full attention to the smallest details.
Accept the present moment.
It is resistance to the present moment that creates most of the difficulties in your life. However, acceptance does not mean that you cannot take action to rectify the situation you are in. What is important is to drop resistance so that you let the moment be, and that any action arises from deeper awareness rather than from resistance. The vast majority of pain in a person's life comes from resistance to what is.