Do not be daunted by the enormity of the world's grief. Do justly, now. Love mercy, now. Walk humbly now. You are not obligated to complete the work, but neither are you free to abandon it.
which I'd re-interpret to,
Do not be daunted by the enormity of the world's grief; you are not obligated to complete the work. But, neither are you free to abandon it. Act with justice. Love with mercy. Walk with humility.
because:
- not everything can be done right away (or overnight), even attitude/approach (sometimes it's what takes the longest). Patience is truly a virtue. So now is optional.
- the original, while good, reads like statement(Do not...)-command(Do..Do..Do...)-statement(You...). Or practice, then theory. I find it more engaging the other way around. To each their own.