The past no longer is. The future has yet to come. Looking by deeply at life as it is in the very here and now, the practitioner dwells in stability and freedom. Even today we must be diligent. To wait until tomorrow is too late.
Death comes unexpectedly.
The Buddha Living in the present by Ven. That would not be possible or desirable. For we do need to recollect the past and to plan for the future at times. Doing what we have to do now well , for that will, in fact, be the best guarantee for the future. And also there will be no regrets when we think back about the past.