@Reluctant_SirBoth Switch and Reluctant_Sir's advice is on the money, but you also need to realize that writer's block, however short of long it lasts, is often your characters refusing to play by your objective. If your characters don't feel your story objective (where they're heading or where you want them to end up) is contrary to the nature you set out for them, it's a guarantee for a protracted case of writer's block—especially if the writing is flowing otherwise.
In those cases, it's best to do a variant of Switch's advice. Take some time off, but you need to be very specific about it. Set out a goal. Determine where the conflict is between your planned story arc and your characters, and once you've isolated it, blank your mind utterly and take a long, long walk, thinking of NOTHING other than the beauty around you.
Invariably, at least for me, emptying my mind while establishing a clear goal like that, I'll 'discover' the perfect solution midway, and will want to turn back immediately. But continuing on, I'll follow it through logically and explore where that newest twist takes the entire story. How much remains the same, what changes, and how it'll impact the other characters.
Trust me, when you reach that stage, nothing will stop the words from flowing, though I have encountered cases of repeated on-and-off writer's block that flows like diarrhea after a prolonged bout of constipation. A few more 'pieces' of the story may temporarilly jam for works momentarily, but once you know how to resolve it, you'll continually be surprised.
What's more, nothing makes a story come 'alive' more than when your characters take over, taking it in all new directions. Then you just have to copy whatever they say as quickly as possible, before they move on to the next thing and leave you behind.
By the way, Reluctant_Sir, your way is actually similar to mine, but spins off into non-productive alternatives, rather than drilling down to the central conflicts, yet the central components are very similar (as is Switch's). But if nothing at all flows, then just write grocery lists, 'found conversations' in the park of a coffee shop, or write abstract scenarios. Whatever keeps your writing fresh is essential however long your downtime is. For an author, there's nothing worse than putting a story aside, as it'll take you months to 'relearn' you craft again.