Just be consistent, and it will work really well. I've cycled on and off all my life, and resumed cycling 5 years ago, aged 41, due to being overweight and unfit. Now I'm 30 again! 
I figured New Years is the perfect time to get excited about me cycling to work and all the great benefits that come with it. I commute 17 each way to work. Most days, I'll ride the bus back home because it's a bit of a grind being 40years old and weighing in at 208lbs on January 1, 2014. Of course, my ultimate goal is to completely cycle round trip each day. Anyhow, each Friday I'll weigh myself in and post results along with current miles cycled with my commute. I figure this is a GREAT way to keep track, stay focus, get support and build momentum. 5,000 miles cycled and 175lbs is my goal. As of now, I'm at 119 miles in. Please wish me luck and support me. Feel free to chime in on your results if you are doing the same. God speed to all of us!!!!!

79 miles is an excellent start!I'm cutrently at 79 miles commuted for this week after cycling in early this morning. I've been cycling round trip this week. I hope to have the energy to cycle back home today. By the way, I had a bad experience yesterday cycling back; Idiot in a truck cut me off as I was crossing an intersection. Long story short, we exchanged profanities and at one point, I thought it would get physical. I'm glad it did'nt. I have be smarter and must walk away from these situations. It's simply dangerous and not worth squat. Anyhow, thank you for letting me share.
Just remember that if you do feel tired, simply ride a bit slower, and I can guarantee you it won't make much overall difference to your commuting time. The time you spend bicycle commuting is time you don't need to spend in a gym, so if the commute takes longer on some days, just tell yourself it's saving you from allocating gym time. As for the motorist who cut you off, unfortunately you'll get those occasionally. If you can recall the numberplate and the truck is a company truck, consider emailing/writing to the company about it, with details such as numberplate, time, date, etc. It may not change their behaviour, but it will most likely make you feel a bit better.
Commuted 128 miles this week on my Cannondale! Along with 105 miles cycled previously, I'm at 233 total miles as of today, January 23, 2014. Looking really good if I continue cycling roundtrip...4,767 more miles to meet my 5,000 miles cycled for the year.
It's currently raining in Los Angeles. Won't cycle in to work tomorrow because I don't trust the vehicles in the rain. . It's so peaceful and beautiful the sound of the rain in the night; the sound of it serenades you to sleep.
Cycled in today and put in my daily 32 miles in. Almost got hit by a dumb driver trying to make a right in front of me as she tried to beat me. Grazed me enough to tick me off. Of course, I yelled at her some "dumb driver" comment. Anyhow, tomorrow is another day. I'm exausted from everything today.....