If you can swim for two hours, you're already healthy

). Try starting in smaller increments. For the first week, just go three days and swim for 20 minutes. Instead of waking up at 6:30, you can wake up at 7:30, and you're still getting a workout in.
The next week, mix it up! Swim for 25 minutes one day, do a 30 minute walk/jog another day, and do 20-25 minutes on a bike the third day. No one, not even Michael Phelps, has the mental stamina to do the same workout for two hours a day every day of the week. It's boring, and it won't be too long until you start to swim very efficiently and don't get much out of the workout anyway.
Make sure you throw some load-bearing exercises in there. Walk, jog, or lift weights at least two times per week. I read once about a 40 year old cyclist who always rode his bike to work out. He had the heart of a 22 year-old, but the bones of a 70 year-old because he didn't do any load-bearing or impact exercises.
But, none of those tips are really motivating, so try these:
1. Find a friend who will work out with you. If you're supposed to meet someone at the gym the odds of you going are much higher.
2. Reward yourself. Even if it's something that sounds stupid like making a star chart. Have boxes for every day of the week, and give yourself a star for every day you work out. If you have five stars at the end of the week, get those earrings you liked, or go to that movie you wanted to see. You can also have two boxes a day and give yourself a star for every day you eat right. Then, if you have ten stars at the end of the week, do something nice for yourself.
3. Write down your goals and keep them some place you will see them every day (like on the refrigerator or television). Do you want to get into that dress for your friend's wedding? Do you want to have enough energy to keep up with your kids or nieces and nephews? Do you want to climb the stairs at the beginning of the day without huffing and puffing at the top? Writing your goals down and reading them every day will help you stay on track.
4. Find ways of working out that you really enjoy. Learn to play volleyball, basketball, racquetball, golf, disc golf (the last three are especially good b/c you don't need to gather a bunch of people to do them). Take a yoga, spin, tai-chi, or step aerobics class. Go outside dressed for running but with the intention of going for a walk. Walk around, enjoy the outdoors, and when you feel like jogging, jog for a few seconds. When you feel like walking, walk. If you look forward to moving, you'll do it a whole lot more.
Good luck! And enjoy getting healthy!