Instead of falling victim to the Sunday night blues, take action. By mapping out your week every Sunday night, you can set yourself up for success.
On Sunday evenings, sit down with your list of important objectives for the year and for each month. Those goals inform every week and help keep you on track. While long-range goals may not be urgent, they are definitely important. If you aren't careful, it's easy for "important" to get pushed aside by "urgent."
Then look at your calendar for the week. You know what times are blocked out by meetings, etc., so look at what you want to accomplish and slot those tasks onto your to-do list.
The key is to create structure and discipline for your week. Otherwise, you'll just let things come to you, and urgent will push aside important.