Timing is everything. The insides of your car's engine is a series of doodads that spin, whirl and go up and down. As long as all those thingies are moving in the correct relationship to each other, your engine runs well and you perceive no problems. But as time passes the gears, chains and belts that connect all those moving parts wear out or even break. Ideally you will keep track of the routine maintenance to prevent major problems. But when you ignore the manufacturer's recommended service intervals, expensive damage can occur.
On most modern cars there is a rubber belt or metal chain called the Timing Belt or Timing Chain which is critical to keeping your engine running right. This belt or chain needs to be replaced every five years or so (check your owner's manual for details). It is possible to do this job yourself with simple hand tools and a long afternoon's worth of time.
Honda products are particularly sensitive to having a fresh timing belt installed. It is not unknown for an old, worn-out Honda timing belt to slip a tooth on the geared cogs that run the engine. That will cause poor performance and in severe cases, expensive valve damage.
Typically, the cost of having a shop replace your timing belt is about $500. But that is mostly labor as the belt only costs about $30. For the At Home Mechanic the hardest part of the job is getting the crank pulley bolt off which is wrenched onto the end of the crankshaft with about 145 lbs. of torque (that is a lot). It is possible to get it off at home without anything other than a breaker bar and a lot of effort. But it is also possible to win the lottery. If you know someone with an air wrench ask him or her to lend it to you. Otherwise you could ask a shop to just loosen the bolt with their air wrench and then get it home ASAP to get it off.
As long as you are tearing that section of the engine apart, you should also change the water pump. The replacement water pump is not that expensive (about $35) and it will aggravate you if you have to come back and essentially redo the whole timing belt job to put in a new water pump. I have made the mistake of NOT changing the water pump while changing a timing belt and it has come back to haunt me.
Changing the water pump is not that hard... but there is a special place in Hell reserved for the Honda engineers who designed the water pump placement on their engines. From a packaging standpoint, it all makes sense to tuck the water pump into that nook it occupies. But to get the old one out and the new one in you will need to remove the timing belt and in many circumstances you will need to move or remove the alternator, power steering pump or some other accessory and their associated belts.
Check your owner's manual carefully for timing belt change intervals. If your car's engine is approaching the due date it is imperative that you either change the belt yourself or have a qualified shop do the work for you. The cost of ignoring that timing belt far outweighs the cost of replacement.