I have been cycling to work for 4 solid months each weekday, except when I have every other Friday off from work. I missed 3 days of cycling due to work-related stuff. Here are some thoughts:
It's 4.5 miles each way. Now, a lot of people, especially don't who don't cycle, will say, "That's pretty good!" implying it's easy. NOPE. It was extremely hard for me to actually cycle this distance without my legs and lungs being completely worn out, even as someone who regularly strength trains, hikes, runs. Like you know, squats deadlifts, HIIT, the whole shebang. When I 'tested' the route, my legs were done for by the time I got back and I couldn't cycle continually, often needing to coast. Road crowns were always a struggle, as were micro hills. Also, it was literally very really hard on my butt/bones and left me sore for a long time. I'd experienced that a few weeks prior with a 23-mile leisurely bike ride, but for some reason I didn't think to get bike shorts prior to that because I thought with the shorter distance that it wouldn't be an issue. Anyway, I quickly invested in some bike shorts and that solved that problem.
On the topic of bike shorts, I also want to point out, because I've heard this in real life and also read this sort of comment on this thread... Just because someone thinks you don't need padded bike shorts until a certain # of mileage, doesn't mean you should listen to them! Ultimately, you should do what works for you. So if people are throwing out comments like, "I don't feel the need to wear padded bike shorts unless I'm biking more than 10 or 20 miles," who the eff cares what they think? Ultimately, it's your own butt that's on the line. If your saddle isn't comfortable, you can change it to something that suits you so that you may not need padded bike shorts, but currently I do not have the patience to experiment with this.
Anyway, my cycling commute became easier for sure, but I think that towards the 2-month mark was I actually able to say my cycling fitness level improved significantly, and I could comfortably go the distance without it feeling completely difficult. Now it's really easy! The only thing that hasn't really gotten that much easier is carrying my bike up 3 flights of stairs every day... even though I've taken the stairs daily for like 3+ freaking years (and that hasn't even gotten easier without a bike, lol).
Also, I'm pretty excited to say the google time estimate for cycling this distance/route is 26 minutes, and when I first began, it would take me 29-30 minutes to cycle. Over a couple months, I whittled that down minute by minute to 19-20 minutes (maybe faster if I didn't obey traffic laws). I have cycled in the rain and in oppressively hot summer temperatures that seems permanently fixed between 95 and 105-degree and will continue this winter. When I wake up in the morning, it's the default routine and I don't question it. Part of that is from utter abhorrence of public transportation in this city (which I used to commute for a month before I decided to 100% commit to cycling), and another part is from simply not owning a car. Wish I could have done this earlier, but the route to my last job involved being on the highway and that just wasn't for me. I love the typical things people love about cycling, like incorporating additional exercise into your routine and feeling less stressed about sitting in traffic. I also feel like it's great for deciding when I want to leave and how fast I want to get there, because that's something you cannot control with public transportation, especially if it's not punctual or reliable.
This is getting kind of long, but I also saw a question in this thread asking what people do with clothes when they get to work.
I use and love the Timbuk2 Raider backpack, which has an inner pocket and flat board which you carefully fold your clothes with, then slip them into the pocket. This helps keep the clothes neat and sort of 'pressed' looking, so they don't get all wrinkly by the time I get to work. I'm sure people can configure a similar system if they don't have that backpack. The backpack itself is pretty solid choice and really inexpensive (I purchased mine on ebay for all of $25). For a daily commute, it's perfect. As someone who eats a lot and is concerned about space to carry food, it can carry quite a bit depending on how efficient one is at packing and if one has a system (of having extra things at work, so they don't need to be transported every day). My partner doesn't even cycle, and he ended up getting this backpack because it's a great size and weight (about 1 lb). For rain, I use put a hi-viz rain cover over it since it's not waterproof. Super inexpensive fix, and great for visibility.
I also leave at least 1 shirt, pants, bra, and underwear in the locker at work so that if I forget something in the morning (and I have!), I won't have an issue. Instead of a full-sized bath towel, I just use a slightly larger hand towel so it fits neatly into my backpack and with the small size, it will dry faster. I'm just rinsing my body, not trying to soak up and completely restyle my hair or anything, so a big towel really is completely unnecessary since I'm trying to cut down bulk/weight for traveling. Since the locker itself isn't big enough to hang multiple garments and doesn't provide enough air circulation to actually dry the towel and the sweaty cycling attire, I choose to hang them up underneath my desk at work using damage-free adhesive Command hooks. And no, it doesn't smell, and it really shouldn't, unless you're rewearing sweaty cycling gear every day or something. I used to hang the clothes on my gear shifters, but I prefer the command hooks since they're out of sight.
Also, this hasn't seemed to be addressed here yet, but sunscreen is really important. I've gotten some weird ass tan lines from cycling, but I tan extremely easily anyway. Lately, I've been enjoying Blue Lizard mineral sunscreens for face and body. Absorbs quickly, not greasy, minimal white cast. Sunscreen is imperative if you want to avoid that leathery skin look later in life. Or if you just burn easily.
I haven't experienced any feet/shoe issues. Since I do not have pedals that necessitate clip-in shoes, I just use a pair of lightweight running shoes with running socks, or sometimes Keds with no socks.
Editing to add: Sunglasses are also imperative. Just like you should never cycle without a helmet, you shouldn't attempt cycling without sunglasses or eye protection of some sort. Road junk and debris WILL get into your eyes, even if it's not a windy day. Ask me how I know this. If you can get sunglasses that curve and minimize exposure, that's even better. Because you will definitely get road junk flying into your eyes from the sides, too.