I have this same problem, so I'm glad you asked this question. To be honest, I don't think I can really outdo the answer from Stephie, but I will share with you some things I've done to help me drink more water:
Make it a habit first thing in the morning
First thing upon waking (after using the bathroom, brushing my teeth, letting pets out), I force myself to drink at least one bottle of water. (If you're opposed to encouraging the use of plastic, this is equivalent to two cups.) If I do nothing else healthy that day, at least I've put 16 ounces of water into my system. A day has a way of making everything but your health a priority, so if you do this first thing, you've done at least that much for yourself. Plus, I've recently read that some studies have been done indicating this is very beneficial to one's health. As a case in point, have you heard of this thing called Japanese Water Therapy? You can read more about it here:
This Japanese Water Therapy is the Key to Losing Weight and Staying Healthy!
Personally, I'd have to be more convinced of the benefits of drinking four to six glasses of water in one session before committing to such a thing and I really like brushing my teeth before I drink my water, but nobody lives longer than the Japanese, so maybe there's something to it.
The other nice thing about drinking water first thing in the morning is that it can help you wake up.
Multitask while you drink, but nothing too distracting
Drinking water is a relatively mindless activity, so you can do other things while you're drinking, but I don't recommend sitting down at a computer while you drink. It can be too distracting. Instead, opt for something you should be able to pull yourself away from easily. Television programs with commercial breaks are good choices as are news broadcasts on the radio (because the news almost always turns to a story you're just not that interested in). If you want, you can also add in some light stretching or yoga.
Make your own drinking games
Some people do this with alcohol, but you can do the same thing with water. Obviously, many drinking games aren't well suited for this. For example, I don't recommend "beer bong" for any beverage. (Who's idea of fun is this?) I also don't recommend swapping out water for beer in "beer pong." This game simply has far too much setup involved and potential to be messy. Plus, it just isn't an efficient way to get your daily water intake. Instead, I recommend something more like the ones you'll find in this article here:
The 25 best movie drinking games to PLAY RESPONSIBLY
Obviously, you don't have to use these same movies. You can decide on others and come up with rules of your own. And you don't have to limit yourself to movies. You could use television programs, radio shows, songs, audio books, etc. Make up whatever rules you want. Your imagination is the limit.
Look at your urine
I don't know anybody who doesn't have to go to the bathroom at least three to four times a day (at a minimum), so this is something everyone can do. When you go to the bathroom, make a habit of looking at your urine. Granted, a lot of different things may factor into how light or dark your urine appears, but in most situations, comparing the appearance of your urine to a chart like this:
can be really helpful, especially in warm climates and/or extended exercise sessions, where that one bottle of water you may or may not have had in the morning doesn't last too long.
Take advantage of mindless activity
Throughout any given day, there are certain activities that really don't require a lot of brain power or concentration. These might include commuting to work, waiting for someone or something (to include being put on hold during a phone call), petting an animal/walking a pet, watching television, listening to the radio, and so on and so forth. All of these activities are perfect for taking the time to add to your daily water intake. Don't miss out on these opportunities to do something good for yourself.
Make drinking water seem new and exciting
Most people I know enjoy trying new things and while there might be fewer choices with water than with something like wine, you can still find ways to get enthused about it. In addition to what Stephie has suggested, I highly recommend cucumber water if you haven't already tried it. If you try it and you like it, buy yourself a nice glass pitcher, free of lead, and always have some of this on hand. Coconut water is another tasty variation on water. If neither of these are on hand, you may want to just opt for a healthy splash or two of your favorite juice. In fact making a habit of cutting your juice with water is a good habit to adopt because juice contains a lot of sugar even if no sugar has been added to it. If you want some more really great ideas for how you can spruce up your water (without adding sugar), read this article here from Wellness Mama:
10 Refreshing Infused Water Recipes (With Fruit & Herbs!)
or this one here from the Food Network:
How to Make Water the Most-Delicious Thing Ever
Psychologists say that fear is the single most powerful motivator. I don't know many who would disagree (although some say it isn't the best one). Regardless, if you happen to agree with this, you may want to do some research on the effects of not drinking enough water. Here's a few articles you may want to read:
Drink Up! Most of Us Could Benefit From More Water
What Happens To Your Brain When You're Dehydrated? The Results Can Be Kind Of Scary
Ten warning signs you're not drinking enough water
All of the above is what has worked for me, personally, but I will confess that occasionally I don't always adhere to these good habits. I don't beat myself up about it. I just make a conscious effort to do better the next day.
And though I strongly feel that adopting these particular habits contributes to my good health, I realize they might not be for everybody. It is very likely that nobody knows, better than you, what motivates you to do something. Take some time to identify what those things are and then find a way to apply them to water consumption. Surely you've had to force yourself to do something at least once or twice before. What steps did you take or mindset did you adopt to make it happen? Choosing habits that appeal to you and fit into your lifestyle easily may be helpful. Setting aside some time for preparation may be another key to your success on this.
Thankfully, those of us who have been averse to drinking water now have a myriad of ways to make it more enticing. I wish you well as you discover what works best for you.