Why do you need to write a blog or to create a podcast? First off, it’s really easy to do. You just need a laptop and a mic. Second, because it lets you refine your ideas and thinking on whatever subject is at hand. And what better way to spend time than to clarify life?
Podcasting in many ways is easier than blogging, because talking is easier than writing. Conversations happen without the need to plan each word or sentence structure.
Neither of these activities will likely make you rich, so don’t do it for that reason.
Both of these activities will show you something about yourself and your ability to create and to stick with a discipline. Do it for that.