Very New To This - Advice/Tips Appreciated :)

Hi Everyone :)

Just over a week ago I was looking through some old photos of my friends & I, which I compared to more recent ones of us all & needless to say I was quite horrified with the difference in myself!

It was enough of a shock to the system to make me want to do something about it - especially considering that we will all start turning 21 next year & there will more than likely be lots more photos taken! I would hate to look back at these potential photos in a few years time & have the same feeling of 'Oh my god look how much thinner I was...' knowing that there was something that I could have done about it.

So I have been on a bit of a health kick for the past week & so far so good - although I was a lot more relaxed at the weekend as I know from previous experiences that if I attempt to stick to a strict healthly diet only then I will ultimately fail & end up gaining more weight than when I started.

I was just hoping that there would some people here that could encourage me to stick to being very good for at least 5 days a week, maybe offer me some tips?
It'd be great to know some basic exercises that are easy to achieve without going to the gym (been there, done that, probably went about 15 times in a year & wasted £672....)?
Does anyone have any ideas on little snacks that feel like they are naughty but are actually good for you?

Any kind of advice would be greatly appreciate & received :)