Hmm...even though lots of people recommended me when i was bored of FM to take a break but usually that doesn't work. How i done it was to find an interesting team to manage.
The best way for you is to look at what you enjoy managing? Do you like...managing lower league teams and getting them to the top and beating top teams? Or do you like managing Big teams but getting them to europe and challenging teams like Barcelona? Or do you want a decent team to build upon with great facilities and decent money with no good history and get them to become a good team and make it a great club? Developing youngsters (regens) to become a top class player?
Just...find your goal.
Another way is to..look on the challenge section of the forum and upon the challenges! The "£50,000,000" challenge is great!