Be Preventive, than to be Reactive.

You need to dig your well, before you feel thirsty.

You need to do exercise and keep yourself fit, before you fell into ill.

This applies to your additional source of Income. 

You need to generate additional source of income when you do not need it, NOT when you need it. Be Wiser, Preventive, than to be Loser and Reactive.

All the Best