Is the only option searching for someone more fit to do the job to replace them?
It is also helpful to get their feedback on why they seem to be not interested in work. Maybe it does not interest them.
Midstream: alignment. Make sure everyone is on the same page and has access to information. Make sure everyone knows what the goal is, why it is a goal, how to get there, what's important, what's less important, what they have to do, that they understand what to do, etc.
Tweak according to people. With some people? Just give them room and don't bother them. They'll come to you when they have a problem and they know when they must come to you. With others, more involvement is required. Tailor your approach to each one.
Downstream: why are they slacking? Is it because they don't know how to do the job? Do they have personal circumstances/problems? Are they lacking sleep? Are they equipped to manage time? Are they not motivated to do the work? Have I talked with them about this?
One good way was to go for a walk one on one, outside of the office. Changing scenery helps. You're walking and talking, and it's amazing that you end up having a completely different conversation than the one you'd have had at the office.
Written emails work, too. When you lay out the problem without attacking the person as in [here is the problem], you get answers like "I meant to talk to you about that but I haven't found the courage. I've been struggling to manage my time and tasks", and you can work from there.
There's sort of an "index" reply here https://news.ycombinator.com/item?id=25367011. Several replies touch on different aspects around the mechanics of getting work done, from reducing the barrier to writing good issues by having templates, to dispatching minutes of meetings so everyone has the same information, to the emails you write to make sure everyone is on the same wavelength, to onboarding documents. Sed "giving a damn" or "what if I disappear" to start.
Some people are very good self starters, they set the structure for their own work, find new challenges, and execute. Though these folks often don’t enjoy the day-in-day-out work. Other people thrive in structure, with lots of good process and stand ups where they see how they contribute regularly. They don’t work well in a vacuum.
Regardless, a team of all self starters isn’t sustainable. And you will need great people who execute well in a structure. If the structure is in place it’s obvious on a regular basis if they’re meeting expectations.
When I was in management, I came close to thinking we should let a colleague go because they weren’t a “self starter” like me. Only to have that person save our company’s bacon once they had a more structured role. They actually wanted more accountability (cause they want to feel their impact). And by giving them more structure, instead of suffocating them, it actually liberated them.
If it is only one person that is slacking off then you can give them a heads up and if not change let the person go. If is it pervasive in the company then you should leave as it would be more difficult to solve that issue. If you can't leave and want to fix the culture this might be a good guiding principle - https://jobs.netflix.com/culture.
That only works until you have ground away any motivation the new employee has.