I find the hardest part about design, is not design at all. It's all the time wasted on planning, tweaking, and dwelling on small features that won't really make any difference in the long run.
Technology plays a big role in this. Our gut reaction when we can't figure something out is to turn to our pal Google and spend time we should be doing other things solving this trivial problem.
Finally when we realize two hours have gone by and nothing has been accomplished, it's too late. There's no getting that time back and often that must-have feature isn't as cool as you imagined.
How to deal with overwhelm
It's a simple strategy but actually following through with it is hard. Write down 3 goals you need to accomplish within the next 12-24 hours. Before you start something new ask yourself if this thing is something you actually must do to get closer to your goals.
I just watched a webinar the other day with Jamie Tardy from Eventual Millionaire and she talked a lot about successful people knowing how to prioritize and only doing actions that move them closer to their measurable goals.
Eliminate the tasks in your daily schedule that don't help you reach your goals. Also think about eliminating things you don't like doing and things you are inefficient at by outsourcing tasks. Don't spend hours learning something new if it isn't absolutely necessary (or enjoyable) for you.