You can invest in a few coins that provide passive-income via their consensus mechanisms.

Have a look here :

https://hackernoon.com/3-cryptocurrencies-to-earn-you-money-while-you-sleep-part-1-3ef340fa4c70
https://hackernoon.com/3-cryptocurrencies-to-earn-passive-income-with-part-2-39c127cd5dd8