He has done everything he can to prepare for the exam, and now he is in a state of 'doing all that is humanly possible and waiting for fate to take its course'.

As the phrase 'If it does not sing, let's wait until the cuckoo sings' suggests, we should wait patiently until the opportunity comes.

He was anxious about starting a new business, but I encouraged him by saying, 'Even a journey of a thousand miles begins with a single step.'