Take a year of unpaid sabbatical leave. If the company you work for actually wants to keep you around, they'll give you this opportunity to take a career break to really have a go at something different.

It works for you and for the company. You get to go out there and see what it's like for startups, the challenges, etc. And then apply those lessons internally.

I know lots of people in their 40's and 50's who have done this, with exactly the same golden handcuffs you're talking about. Some of them came back, and rewarded the company's trust with a revitialised vigour. Others decided to leave and pursue their chosen option.

Example: A guy I know was a senior Account Manager at a major telco in Australia. He decided to start a scuba diving business in Thailand. He took 6 months to 'test the waters' (sorry, that was a terrible pun) and decided that was his dream.

Life is short. Live it to the full.