Retirement can be one of the most stressful times of a person's life. Talking about it is good, but they may feel pressured into it. Sounds like they are not quite sure how to draw down their 401k's, a little knowledge goes a long ways. Most people may know how to save but not what to do after that, so are you showing them or help show them how to do it? Have you helped them picture what their retirement would be like? Do they even know what their retirement might be like? Maybe they have a lot of friends at work and feel like they are serving a purpose? Or maybe they hate their jobs and it really is just fear?
I tried to convince my Father to retire for 5 years. I told him that as a federal employee on CSRS retirement system after 32 years of working that he was working full time for like 25% of the pay. I had been telling him this for years, then he met w/HR after a retirement seminar and they told him the same thing and he gave like 7 working days notice. Sometimes an outsiders input will help, sometimes just picturing what they are going to do w/their time will help.
Maybe start w/helping them see what their ideal retirement would look like, how much they will spend in retirement, how much they have, and how easy it would be for them to do it.