Running
Parque Ãu Guazú
Lots of elite Asunceños work off the stresses of their days at Parque Ãu Guazú, located just outside Asunción in the city of Luque, on the way to the airport. There's a great paved 9K loop for jogging or walking.
Teaching English is a possibility, but without a visa it can be difficult and wages are low. In a country such as Paraguay with widespread underemployment, obtaining paid work is almost impossible for foreigners. Volunteer work in poorer areas of the city is easy to come by.
Learning Guarani Language is a great opportunity to get into the paraguayan culture. IDIPAR (http://www.idipar.edu.py/...) institute has good choices for that.