The mr in the house is clearly an example of what you can accomplish if you set your mind to it.
My best advice is to not try and measure yourself by him or any yardstick for the first 6 months. Make a goal of exercising a minimum of 4 days a week. Shift them around if life happens. Make one of those days a long ride. On the other days do rides if you parts aren't hurting too much, or simply get out and do an hour of brisk walking
Dont get discouraged, start again the next day if you fall off. Don't get discouraged if it seems you aren't making progress...it's hard to see the progress if your measuring yourself against someone more accomplished.
I did a running program over the winter with my wife. She made it all look so easy. She would do a run, and come home and jump right back into other activities. I would come home and die.
It made it very hard for me to see that I was getting better, although slowly. Oddly enough a buddy at work was the one that pointed out to me that 6 weeks ago, I couldn't run down my driveway, bit today I was running 3 miles. 12 weeks after that I ran 13.1 miles.
Change you eating to support the getting in shape, and get some more encouragement from the scale each week. Don't get too excited if it doesn't go down the first month...I know mine didn't. But since thanksgiving i have lost 30 lbs and it keeps coming off very slowly.
Best adivce is really just the Nike slogan...just do it. Try and find a small way to be active each and every day. I take the stairs everywhere I go now, and oddly enough I always beat the guys in the elevator or escalator. I travel for work. So I get some odd looks lugging my suitcase up the stairs, but it works for me.
Mynpoint is don't let perceived difficulties stop you from exercising. There is a treadmill or elliptical or street nearby somewhere with your name on it, if you can't get on the bike.
And one last thought, it's going to be hard, most people give up because it's hard. Find a way to keep going.