First of all, let's face the facts. Working 9 to 6, you won't have any time during the day. If you choose to have a second job during the evening hours, you'd get burnt out very easily. Chances are that you might under-perform in both the jobs. I recommend having a side business rather than a second job. Some investment of money and time would be required at first. I have come up with a few options that would require less work from you but would be a decent second source of income.
Finding the time and motivation to make extra money can be tough, especially if you’re already working a demanding day job. However, whether it’s paying off a debt or saving up for a major purchase, there are times when one income just isn’t enough. If you can’t face the thought of putting in extra shifts on top of your 9-5, you need to find another solution – one that doesn’t feel like work but still brings in the cash.

An obvious example is over exposure to bank stocks, which have been excellent investments for over a century.  Though a foundation of most portfolios, bank stocks do involve more risk at certain stages of the economic cycle than many realise.  Being less exposed to bank shares in the last few months could have preserved some capital.  So, a more diversified approach can help mitigate some of these risks.