Have enough/a lot/too much on your plate
Definition 1 of 2
Pro Tip 1/3Metaphoric Usage
The phrase often symbolizes managing lots of responsibilities like juggling multiple tasks. 
With his finals and part-time job, he certainly has enough on his plate.
Pro Tip 2/3Casual Context
It's commonly used in everyday conversation, not typically in formal situations. 
Sorry, I can't join the committee right now — I have too much on my plate.
Pro Tip 3/3Emotional Weight
Can indicate feeling stressed or overwhelmed, not just physically busy. 
Ever since the move, they've had a lot on their plate and seem stressed.