I have my first meeting as a new manager?

Next week after 4 weeks of training I will start managing the team of 12 employees. I was meeting them for 4 weeks we got to know each other, worked together side by side, I saw all the mistakes, unproductive, untolerable behavier. This is housekeeping evening shift in the luxury resort-emploees have been there for 25 years and they created pattern of doing nothing and pretending doing 100% and productivity suffers.
I was hired to change it and break their patterns of layziness and lying. What am I supposed say on my first meeting, remember they are very powerfull (25years of service and union members) They can easily go against me.

I had been executive housekeeping manager for 3 years, but built my team from the beginning and never had experience with this kind of behavier.

Thank you for your answers

oooh that is a difficult job!

At your first meeting I would announce that you plan on making some changes (but don't announce the changes yet).
You might also say that you plan to include the staff in decision making as much as possible (some sort of vague statement that makes them feel valued).
And most definitely thank them for their many years of service and that you are sure they have much to teach you about the resort.

I would institute changes slowly so you don't antagonize them immediately. You will really need to feel it out as you go, so keep the first meeting generally vague.

a HINT: I'm in a completely different industry but I had a similar problem of the evening shift not working hard enough and not completeing their work. I still have not solved the problem as part of the issue is bordom and lack of supervision. However, I tried rotating the evening staff into a daytime shift occasionally. Believe me, it was a total wake up call for some of them. There were more people on shift, more supervision, and more work to be done. It really showed them the amount of work we expect to get done in a shift.

Is it possible to induce a reward system into this equation? So if the GROUP meets objective xxx (faster, better quality....define some simple measurable goals for the GROUP, not person) everyone will somehow get rewarded? You have a difficult job. Don't go in there and announce you are going to make some changes....they will get worse...lock you out. If you can induce a reward system concurrent with making change it will be easier. Being union members is sure not going to help! (had that problem as a high ranking fed. gov manager with unionized civilian employees!!!)

Let them know that you will be "walking the floors"....will be more visible...keep notes on what needs correcting....don't attribute individual names to anything at this point. Gradually introduce change, along with recognition/praise.
Share the productivity measures with them...then enforce...and as you know you must keep notes on all employees not just the problem ones or you can be charged with discrimination....Good Luck!