Then after some time, or from time to time we can be back to that notes and see that we can be happy for having such eventful life, for breathing, for living, for having friends, etc. For we generally are prone to think in term of ''right here and now".
As an illustration, an employee can think of how bad is having to wake up and raise soo early in the Mondays mornings and forget that his/her job made him/her enjoy the weekend, sometimes it can give him such big "headaches'' and Herculean tasks but it also sometimes may give the opportunity to travel to other places, to know lots of nice people etc...
The gist of it, is that by taking such notes we may become less immediatists. To me, it doesn´t take to put it to paper, just a mental note would do, since problably it´s about being grateful and having a positive (but realistic, though) attitude towards events in life.
But yes, since we have such short-lived memory, having something written might be a good thing.