"Nothing, not even pain, lasts forever. If I can just keep putting one foot in front of the other, I will eventually get to the end." Applicable for running and life! - I HAVE to remember this while training and then doing the miles.
What people often do is they put off something for so long that eventually they will just start telling themselves it's too late. No it's never too late, a year from now you will have wished you started today.