I tell my clients that the best way to accomplish decluttering is to take it in pieces. If there is a stack of old mail you need to get through, tell yourself you will work on it for 15 minutes and then set a timer and do whatever you can in that 15 minute time frame. Then, leave the rest for tomorrow when you will do another 15 minutes. For the future, you will have just the current mail to go through each day and you will immediately trash, file or process it when you do so. This way you won't see that growing pile in the future. This 15 minute rule works great with other organizing tasks too. Give it a try!