If the pneumonia you have is viral pneumonia then it usually doesn't require any treatment and goes away within 1 to 3 weeks without any treatment or hospitalization.
If the pneumonia is bacterial pneumonia then that almost requires hospitalization and should also go away within 2 to 3 weeks with treatment at the hospital.
It's always a good idea to see a doctor if you have pneumonia so they can diagnose what type of pneumonia you have because if it's bacterial pneumonia then you need antibiotics otherwise if the bacterial pneumonia is left untreated and gets worse it could lead to death.