Thank you to Sisterhood of the Rose, where I first saw this.
Source: Tao and Zen
"To dwell in the here and now does not mean you never think about the past,
or responsibly plan for the future. The idea is simply not to allow yourself
to get lost in regrets about the past or worries about the future.
Letting go gives us freedom, and freedom is the only condition for happiness."
Thich Nhat Hanh