The secret to persist with commuting on the bike is to remove friction as much as possible.
Lots of greats suggestions here. I would add a few more points. For me the biggest thing making me pick my car in the morning was thinking "But what if I want to...." Over time I chipped away at the "what ifs" by figuring out how to secure my bike, where I could get coffee before work and a beer after, where to pick up groceries on the way home, and how I could freshen up at work if I needed to. So:
- Keep a stash of wet wipes (the big ones made for camping), deodorant, and a fresh shirt at work in case you have an unexpectedly hot day or an unexpected 9am meeting with a client. - Learn how to secure your bike, and always carry your lock(s). Then you'll always be able to grab some groceries or have a drink with someone after work. - Get familiar with the amenities that matter to you on or close to your route. If you're a coffee fiend and run out of coffee in the morning, you'll want to make a detour. - Buy a bigger bag than you strictly need. Riding with a half-empty bag in the morning is the only way you have the freedom to buy groceries or dinner on the way home.