When I first started riding I could only handle about 5-6 miles at a time. I tried to ride that much everyday though, and after about a month I decided to take the plunge and ride my commute on a day off (20 miles round trip and looks very much like yours in relation to elevation change). The wind was in my face at about 30 mph the whole way there, and it took me over an hour to do 10 miles. I decided that until I got into better shape I wouldn't want to commute if the wind was more than 10 mph. After commuting to work for 2 months I was able to keep a pace between 17-20 mph. There was a huge hill (bridge) at the end of my commute going over a highway. I would pedal at a crawl going up that thing at first, but after a while I could pedal up the thing without standing. It all just takes time man. Oh yeah, in doing all this riding I went from 215 to 185 within 6 months. Not too bad considering I didn't really stick to a diet, although getting vigorous exercise will make you lean toward more nutritious foods. I would recommend what others have said, to train on weekends, but take the toughest hilliest route you can, and make it your *****. You'll be zipping along incline or no incline in no time.