Debt collection on a commercial property.

[Franz Fernanez]

I have a tenant that has been delinquent in paying up the lease on my office condo. Because of a previous business commitment with the tenant, I have been quite flexible in collecting rent. (Not a good idea!) How do I go about collecting unpaid rent? Do I need legal assistance to write a demand letter? The lease has since been terminated so I could lease/sell the property. The property is in the Chicago suburbs.