You ought to be able to maintain your bikes for rides- Oil the chain- adjust cables to get the gears working right and put air in the tyres. If you can't do that- then it will take less than 12 years to wear out a bike. A Lot Less

But if your mechanicing skills are limited to ride mainetenance and no more- Then leave the bike alone. A friendly LBS is not expensive and they do a better job than you.