Do you think we're getting to dependent on technology?

[Tiberius]

For example, air conditioning is weakening people's bodies ability to adapt. They sit in a warm house/office all day, then walk outside and it's freezing cold, and they get the flu.

This happens to everyone, and it has nothing to do with air conditioning (I'd like to see a paper that links to two if you have it though). When we go into an environment that is too cold for us, and we don't protect against the cold properly, our body defenses start to fail, which means the cold virus can easily infect us.

Or builders now use powertools instead of working by hand which means they aren't building their muscles as much.

Builders have to lift power tools, and in most cases also have to carry bricks, beams, etc as part of their job. It's far cheaper to hire men than getting a robot to do it. The demand for builders is still there, and the requirement for builders is to be strong, so they have to workout.