Yes, I've started a small business. Or, rather, have co-started such a business. So, I'm not completely alone (though occasionally I feel like it).
I'd say - it's probably mostly fun if you don't depend on it for your livelihood. If you do, prepare for at least a little bit of pain. And, yeah, it can be kind of stressful, especially if you have deadlines and impatient and demanding customers/clients. In fact, it can be stressful just to perform up to the level that puts you even with competition, much less actually beat them all. If the competition/need-for-survival aspect doesn't affect you all that much, then I'd expect stress levels to not be all that bad.
Hm, problems and pitfalls that I've faced... Well, as you mention, there's that whole stay motivated thing. Sometimes work can get very boring and tedious. It's sometimes hard without an actual boss to set time schedules and such. I can tend to procrastinate and forget things.
I've found it's hard for me to keep track of my hours and finances. The hours thing because I tend to skip around when I'm working. Sometimes I'll work consistently for a couple of hours on one thing; often I'll work on something for a little, then work on something related, then work on something entirely not-related, and in between do random other things; or sometimes I'll spend time not doing anything - which I feel guilty about.
I also tend to attach emotions to things and not be objective. For example, there'll be a relatively easy task when you look at it pragmatically, but it's related to something bad that happened (or is happening or is going to happen), and I'll shy away from it. Or, I'll work quite hard on something very complex and not entirely important because it appeals to me and/or
isn't something else that I
don't want to do.
In terms of finances... well... I'm pretty sure I fail at that. Not that I spend a lot, no. I'm usually pretty thrifty. But keeping track of expenditures and income and taxes and tithe and where everything goes and where it comes from and where it gets kept and all the little numbers.... I try, but fail. I'll keep track of those things for maybe two weeks (I made it a few months once), but then I forget a few times, lose heart, and give up, until I have a big mess to untangle, resolve to be better from now on, keep track, loose track, etc.
Another thing that I've only recently begun to see in myself is my tendency to sort of... hm, how to put it... expect the other person to help me solve problems. For example, when communicating with a contractor about what I need from him, I've found myself narrating the whole problem and then kind of ending on a sort of question of "now what?", when what I really need to do is think this all out for myself ahead of time and only really bother him with what I specifically know I need from him. I mean, I do want to make sure that everybody involved has all the info they need, but I think sometimes I tend to expect to sort of just lay out the info and then have the people around me figure out what to do. Which doesn't really work if there's no one around who either should or wants to do that. So that's a pitfall, one that I've just become aware of.
I mentioned above that I find I often lack a practical and pragmatic approach. I do what I can, and it usually suffices if I try hard enough (or it seems to), but often I get the feeling that there's a better way I could be doing things or that I'm missing something important. It's hard for me to be grounded and sensible and realistic and utilitarian and purely logical all the time.
I find I tend to expect good things to come to me instead of me having to go out and get them for myself. I mean, I know in my head that it isn't really like that, but nonetheless I find that is a tendency in myself. So that's something I'm constantly either having to force myself to do or feeling guilty for not doing so.
...
On the other hand, owning/running a small business is excellent for getting to multi-task, not being stuck with just one thing to do all day, challenging you to grow and learn constantly, providing opportunities to network, promoting creative thinking, and allowing you to do something you like on a relatively regular basis (provided, of course, that your small business is centered around an interest of yours). Among other things.