It's impossible, I think, not to look ahead, not to plan, to worry, to anticipate. Even though we teach ourselves, through our own experience, that all that energy spent is needless, I think it's hardwired into us.
At any rate, the day arrives, presaged by all that anxiety, and maybe it's exhausting. Maybe it's terrible. Maybe it's wonderful, but inevitably, there is beauty there somewhere. There are moments of quiet. There are snippets of peace. Find those and rest in them before you can leave the day, the week, the year behind, congratulating yourself--sincerely--for being brave for having walked through it at all in the first place.