Age has a lot to do with battery strength. But I would check all the connections and make sure they're clean and tight at the battery, solenoid, starter, frame and negative terminal. It can be jumped from a car, just match the terminals. If it turns over quickly with jumpers, but barely turns over on it's own, it's probably time for a new battery. Check the connections first.
'90 906 Paso
It's not just a Ducati, it's a disease!