[X] Of the present. The fragile sensation of holding each other's hands as everything else comes apart. Fear and trust intermingled. Pride in raising others to a righteous purpose, guilt that in the end your dreams can only be made real through violence. Need.
The past is a cassette of film, worn by dust and light. The future is a spreading web, with no reason in it's meaning.
More seriously, Bleach is a world where the past and future ARE fluid, as shown by Tsukishima and Ywhach. Only the present is set in stone, as the rest can be altered by those with the power to do so. Additionally, the state of the past is beyond OUR influence, and we have already extracted meaning from it. Dwelling too much on what could have been is going to be distracting. Conversely, the future is a dream right now, and relies solely on what we can accomplish NOW.