roll (one's) sleeves up
To do or get ready to do something difficult, intense, or demanding. Enough dawdling—it's time to roll our sleeves up and start unpacking all these boxes. If you want to pass this test, you need to roll your sleeves up and study.
roll one's sleeves up
1. Lit. to turn one's sleeves upward, exposing the arms. He rolled his sleeves up and began to wash the dishes. Don rolled up his sleeves so he would be cooler.
2. Fig. to prepare to get to work. Let's roll our sleeves up and get this job done! Jane rolled up her sleeves and got to work.