I think part of the reason I enjoy cleaning is that it's usually a pretty painless activity that provides instant gratification. Mop a hardwood floor, enjoy its gleam; make a bed, walk into a more peaceful bedroom. Cleaning the grout of a tile floor is nothing like this: gratification is delayed, and on top of that, cleaning grout is one of the toughest cleaning jobs in the house. Following are some ways I've found to make it a little less taxing.
Clean up spills immediately. When you spill some spaghetti sauce or dribble some wine or the baby flings yogurt off the spoon and onto the floor, wipe up the mess as soon as possible so the stain doesn't soak into the porous grout. You'll save yourself a lot of scrubbing later.
Keep a spray bottle handy for fresh stains. Fill a spray bottle with a solution of one part hydrogen peroxide to 2 parts water. When a stain occurs, spray the solution and scrub it in with a small, stiff-bristled brush. Let it sit (this is key) for about 15 minutes and then wipe clean. You may have to repeat. I like to incorporate this job into my monthly cleaning routine.
Have the right tools for the job. Cleaning the grout of an entire floor space is not for the faint of heart. It takes time and hard work. Having a brush specifically designed for grout cleaning makes the job much more bearable, and your knees and back will also thank you for it. I prefer a brush like this with a long handle, so I can stand and put my weight into the scrubbing.
Be patient. Key key key point to cleaning grout is to let your solution soak into the grout. I like to use a loose paste of OxiClean and water, which works very well — if you let it sit. Once you wipe it up (which you may have to do several times to get rid of the residue), you'll have to wait again to see the difference in your grout. Wet grout doesn't look too clean. I use fans to speed up the drying process.
When all else fails, fake it. I used to scoff at the notion of grout "cleaners" that are actually essentially paint. But when I saw this post on Young House Love, I started singing a different tune. Our own Nelly had success with a similar product here.