I always think that our brains are used to think, rather than remember. Instead of trying to remember all you complicated assignments (work or personal) inside your grey matter, it is better to write them down into a checklist so that you can focus on
thinking.
I only use open office word processing to manage my check list. At the top I create a calendar by using table and mark down important events on that month (and include the following month if any important event that need to get ready).
Then I put an UNCOMPLETED TASKS table, which contain 2 columns: task description and ETA (Estimated Time Accomplishment). Then follow by a KIV TASKS table and a COMPLETE TASKS table, which have the same columns as UMCOMPLETED TASKS (Add in any necessary column to suit your need).
Whenever I get an assignment (from email to someone to do a project), I set a ETA for it and add it in UNCOMPLETED TASKS order by ETA. After it is done, I move it to the COMPLETED TASK table. For assignment that is not important and not urgent, put it in KIV TASKS.
So now your assignment is very simple, try to reduce the number of row in UNCOMPLETED TASK table. Below is my checklist format:
Calendar
Uncompleted Tasks
KIV Tasks
Completed Tasks