Show your bike some love
Properly maintaining your bikes components will keep them from failing prematurely. Consistently check to make sure your tires are inflated, chain lubed, bolts are tight, the suspension is dialed, the brakes properly engage, your front/rear derailleurs are adjusted, and don't forget to clean it!
Pay special attention to your drivetrain
Clean off the dirt and then apply lube. Infrequent cleaning and lubing will accelerate wear on your chain, cassette, and chainrings.
Cables don't last forever
If your shifting feels a little slow there's a good chance your cables have begun to fray and that they are binding in the cable housing. You should change out your cables and the cable housing yearly or whenever the shifting starts to feel inconsistent.