This is a mind-numbingly slow game...

[Matthew Trotter]

By the time I'm 40, I see myself managing 10+ rental properties. That's in about 8 years from now, and I think it's an easily attainable goal. The problem is that it's soooo sloooooowwwww. I've got two properties now, and I'm house-hacking my way to 10 total. 

It'll take another year to save up enough for another purchase, so until then, all I can do (real estate wise) is listen to BP Podcasts. What are some things you have done in times like this where there wasn't much to do but wait?

[Nathan Emmert]

Live.  

As time elapses, your life passes.

If you want a less pragmatic view, are you building the skills required to accelerate your life goals?  You don't need cash to invest, though it's much better.  Why not use some of the next 87,600 hours you plan to wait to hit your goal to learn to invest without cash and maybe speed the process up?  Or get a better education to increase your W2 pay to build savings faster?  Or flip a house on the side to bring in extra income?

You can also spend that time learning to maximize your current investments. Can you add an extra unit to your property? Have you done a cost/benefit analysis of coin operated laundry? Would some cheap kitchen upgrades increase the rent and give a large positive ROI? Have you appealed your tax rate or looked at separate metering of utilities? Have you optimized the lawn/snow care for the property to lower your expenses?

It really comes down to goals.  Are you a passive investor... an active investor... a real estate professional?  Decide how to define yourself and act appropriately.  Being a passive investor but expecting it to be your full-time hobby really doesn't jive well.