I found the Insanity workout series very good when I was trying to improve my fitness. It's mainly bodyweight cardio exercises and will drastically improve your fitness, but it's also definitely not for everyone.

I found having a focus and instructor motivational, while my wife found it boring and eventually monotonous. She greatly prefers to take group classes at the gym. Probably the best thing to do is find a hobby that is also physical activity, enjoyment is a hugely important part of maintaining motivation.

What you will probably find though is that once you have been exercising for a few weeks, you start to gain motivation from your own improvements, further reinforcing your motivation. It's that first three weeks of so that are the only real struggle.

As others have said, you only need to upgrade once you become frustrated with the limitations of your current camera.

It's easy to fall into the trap of thinking that a 'better camera' will make you a 'better photographer,' but it's much more important to learn the theory of photography and you may be surprised what you can make your point and shoot once you take it out of auto mode.

Having said that, it;s probably much easier to get your head around photographic theory with a larger camera, because they are designed for the creative controls to be within easy reach.

To specifically answer your question, a DSLR camera has a larger sensor than your specific point-and-shoot, and that brings many advantages with it.