How long do stock shocks last?

[TNurburgring]

I own an '08 MX-5 with about 37.000 miles on it. It has Eibach Pro-kit lowering springs installed. These were on the car when I bought the car, so they could be installed when the car was bought new (I am not sure). Should I worry about replacing the shocks soon?

[TNurburgring]

Thanks for the replies! I didn't know shocks last that long. No reason to worry for me, because my shocks are still "young".