Time repeats itself once and again

There are moments in life in which one realizes how everything changes in short periods of time. It is in those moments where one realizes what he/she was and what he/she is and asks him/herself what he/she'll be one day.
Thinking continuously about the future doesn't solve anything since it always happens something in the present that will send your plans to hell.
This happens in each aspect of life. With feelings, with your own personality and maturity (what we hated in the past, now we can love it and vice versa), with our studies or with friends.
Thinking continuously about the past doesn't solve anything either. The past is past and nobody can change it.
So, let's live the present with 'certain intentions for the future'. If I have learnt something after 21 years is: don't worry, because the majority of your plans will go to hell because one reason or another. We have to live more the day-to-day. It is the fair thing in this stressful world. Let time pass... then, when we realize it, we well see that twenty years are gone and we are like in the beginning, with the same doubts... with the same anxieties...