Work is physical or mental activity that adds value to the economy. Such things as digging ditches for necessary drains, building roads to somewhere (as opposed to bridges to nowhere), writing software code for a start-up, cooking a restaurant meal, growing wheat etc.
There are many other sorts of activities, such as the play of the young, amateur sports, whistling and sending out tax compliance forms, but these are not work, for they add no commercial value.
Just doing something and being paid for it is not necessarily work. Look no further than public servants for an extreme example of this. Yes, they are active, but no, they do not add value. Worse, their job is often anti-work, they subtract value from the economy by enforcing regulations and taxation.
Money is an irreplaceable tool for increasing and smoothing economic activity. Such activity is what we know as work and it is how wealth is created.
The utilisation of pseudo-money, AKA fiat, is how wealth is destroyed. It leads to misallocation of production and capital and thus diminishes and sometimes entirely negates, the value of work.