Actually, without invalidating WS2's fine answer there is the British English idiomatic phrase (lets) crack on: “Crack on” can mean either “start” or “continue”, depending on the context and progress of the activity
We’ve got a long journey ahead of us. Let’s get cracking. (Let’s go / start now.)
I’ve still got a lot to do so I better crack on
TFD defines it as:
to continue to do something as quickly as possible
Curiously, in Australian English, to crack on to is:
seek to form a sexual relationship with (someone).
Thus depending where or from whom the OP heard the following expressions; crack on, crack on to, or the Irish craic as in
Séamas: "Come into to town, it's great craic!
either one of the three may be correct.