One of the best book I have read recently was the One Thing by Gary Keller and Jay Papasan.
The book is focused on the core idea that in order to make giant progress on your goals, focus on the one thing. Success is often the result of narrowing your concentration to one thing.
I have personally experienced this many times. I am more productive when I only have 1 priority to focus on.
In the words of Productivity guru, David Allen - There is no such thing as priorities. Priority is the right word. Priority is always singular and you can have only 1 priority.
The idea is to focus on one thing at a time and move to the next thing only if you have achievied your first thing.
Multi-tasking is a lie. When you are multi-tasking, your tasks are going to take more time. As we are multi-tasking, we are doing a lot of context switching from one task to another, which brings down productivity.
To make giant progress on your goals, focus on the one thing at a time. Our brain functions in such a way that when we focus on the one thing, it improves productivity.
Multi-tasking is a myth and should be avoided.