In the original Sanskrit, the word translated here as ‘work’ is ‘karma’. In the the preceding chapters Krishna has taught Arjuna about spiritual practice during activities, ie. karma yoga, in which the mind is made calm during activities by various means.
Now, in Chapter 6, Krishna teaches Arjuna that eventually the path of work leads to the path of stillness, and it is through stillness of mind that one advances in yoga. The rest of Chapter 6 explains in more details how this is to be done.