Use the Pomodoro technique
The Pomodoro technique, created by Italian entrepreneur Francesco Cirillo, teaches us to work with time, not against it. It’s about tracking your time to get a more realistic handle on your projects. Especially on how long specific projects and tasks take you.
Work in short, focused bursts of 20/30/40 minutes. Then you give yourself a brief break to recover and start over. This will break down your large complex task into manageable intervals. Once you start a task, you aim to finish it before attending to urgent but unimportant tasks.