No worries there. I eat quite healthily - not too little and nothing in excess - and I drink more than 8 cups of water a day.
Speaking of which, I am a practicing pescatarian (i.e. I don't eat meat, aside from fish), so that might have something to do with it as well, but I really don't want to change my diet because I don't like red meat for one and also for health reasons. High blood pressure runs in my family.
Yeah, I forgot to mention in my last post that I used to be somewhat of a gymnast, so I'm not afraid of doing a lot of hard work or physical activity. In fact, I am still a relatively active and fit individual, but I always manage to look skinny and not toned. I think the issue might have more to do with the types of exercises I need to be doing, rather than having to do more of the same. Thanks to everyone for their ideas. I will try them all out and hopefully it helps.