Yesterday, you said, "Tomorrow". Just start meow...er, now.
What are you waiting for? Seriously, what? That thing you have to do? That place you need to be? That project you need to finish first?
That's life! There is always a 'thing' that could stop you getting started on your fitness.
Or you could realise that's life, it will continue to be that way, and you're always making adjustments, so you may as well get started anyway.
Today.
