1. I love fashion and I dress nicely... I can't be bothered changing clothes unless it's into pjs and I'm going to bed
I believe in fashion as well. I ride my bike to work and back at least 3 times a week, making 150km a week at least, and you won't find me in unfashionable clothes either. I wear a nice outfit to not look stupid. You can get some nice clothes in the sports section of several stores, so on this point you're being rediculous.
2. I don't like to sweat
And that's why we invented showers. I like showers, as hot and steamy as possible. But would a shower have any function if you haven't done a thing and are actually taking a shower and not getting any cleaner with it? Besides, sweat is important for cleaning the body. Lots of garbage leaves the body by just sweating a little bit.
3. Gyms cost money
Who said you have to go to a gym? I ride my bike to work, as do numerous others. I see loads of people like (or unlike) me, who are still riding their bikes to work. It's exercise and it doesn't cost a lot. So far, this exercise has saved me money instead of cost me money. Other options are running or doing yoga/pilates. Check out youtube, it doesn't have to cost a lot, some options don't even cost a thing.
4. I don't like exercising in public
If you feel like you are exercising, you might be doing something wrong. It's not just exercise you're doing. You're toning your body, and you're cleaning it. Besides that, you are having fun (maybe not at first, but give it a few shots, you will start to like it. Scientists call it: endorphyns), you can even listen to your favorite music or radio station nowadays while working out. What more do you want?
5. I get headaches and dizziness last time I exercised so I'm scared
You should be scared. That's what little to no exercise does to your body. If you haven't exercised for months (or maybe even years) this might happen. You're digging in too deep. You want to go running? Start by walking, you can gear up any time you want.
6. I don't want to get bad skin from sweating
On average a person sweats about 6 tea cups a day. If that doesn't give you a bad skin, sweating really badly won't either. The body is actually pushing out all garbage, which should even make your skin look better.
7. I have a bad back
So have I, but that didn't stop me either. You will have to push yourself at first, but you will fall into a certain rythm, making you stay with your exercise.
8. I believe I can lose a further 6kgs with diet alone (I'm 19 and I believe in my metabolism LOL)
Sure, you might be able to lose weight by dieting. Dieting however is not always the solution. Did you ever think your weight problem might be because you're not exercising enough? You have stacked loads of trash in that body, that are now leaving the body by not nurishing your body enough. Does that sound right? No it doesn't. That's why I have more faith in exercise than in diets. You should make sure you eat enough for your daily routines. Whatever your body has stored in the past, you can burn by exercising.