Pay mortgage or invest?

[Chris Mandle]

I bought the coop where I live 1.5 years ago. 20% down, 80% financed. I feel pretty good it’s a gentrifying neighborhood and could eventual sell and make some $$ on it. However I think this will take at least 10 years. When I purchased I did not know I would want to get into investment real estate. I am starting to educate myself, but  now  I am torn if I should aggressively save up to pay down the principal or save up for an investment property. Any advice?