Are there any creative ways you’d recommend for me to identify and approach motivated sellers or uncover foreclosures?

These people have been labeled as "motivated sellers."

Kept those agents motivated to answer the friggin phone

This works best when the seller is motivated and open to flexible terms.4.BRRRR Strategy (Buy, Rehab, Rent, Refinance, Repeat)– If you find the right undervalued property, you can finance the rehab with short-term funding and then refinance into a long-term loan, pulling most or all of your money back out.5.House Hacking– If you’re open to living in your investment, you can use an FHA loan (as low as 3.5% down)to buy a multi-unit, live in one unit, and rent out the others.

What's your motivation to get into real estate investing? 

It sounds like you're on the right path to achieve the goal of 20 rentals. 

Part of the motivation for congress writing Dodd Frank was to clamp down on the investors offering preditory terms re  rent to own and seller financing and that view has carried into craigslist rent to own adds and you say zillow. 

They then obtain a favorable appraisal and achieve decent cash flow in the earlier years.

Clearly identify what you want to achieve in real estate and use that as a guiding force throughout your journey.

I'm going off the understanding that you still need to spend 500+ hours in the business to achieve material participation (please correct me if I'm wrong).