I personally am amazed that anyone would want to keep a cat indoors all the time. Seems all wrong to me. Mine all like to be out and about doing the rounds of friendly neighbours' laps (& kitchens) and meeting up & mooching around with the other cats.
Amoret's two cats were confined until 6 months old (on the advice of a vet) - but were clearly absolutely desperate to get out. They roam free now and are happier for it. They might have a shorter life, but it is a happy one.
My oldest cat spent the first 5 or so years as a house cat by choice, and would get really distressed if taken outside. Then he spent the next 4 or so years as a garden cat and would get really distressed if taken indoors. He does a bit of both now. Mad cat - but I think its better for him to do what he wants. I see it as living with cats, rather than owning cats.

Kris