Check out the 4 Hour Body if you can.
A very important point is not to overwork yourself. Most workout routines don't really work well, so people overdo them. 3 minutes of running does way more than 60 minutes of comfortable walking. A lot of people like me start off really lagging behind in physical health, so what most people advice is just crazy - I couldn't even do 1 push up, much less 20 push ups and a 15 minute jog as was recommended for newbies in some health magazines.
Since you're still starting out, burning yourself out and taking long rests is going to discourage yourself from exercising. I'd recommend you aim for a point where you can exercise daily. Do the heavy duty stuff once exercise becomes a habit.
Tim Ferriss recommends the rule of 10 reps for strength training - limit yourself to 10 reps at most, 3 times a week. That means lift heavier but not hard. This is to maximize strength gain while minimizing recovery time. It's great if you're don't want to be sore at school/office and many athletes follow this because they want to focus on improving strength without recovery interfering with their other training. The Russian National Weightlifting Team does 2 reps.
Go with what nenjin said about finding something to lift 5 times. Then multiply that weight by 1.2x. Lift that weight up to your knee height and drop it. Don't lower it or you'll waste energy recovering from hamstring injuries. Do this only once a day at most, you'll feel the strength boost within a month. I'd almost recommend doing a single lift if you're looking at pure strength (not so much big muscles) because it minimizes recovery time. Different routine if you want to bulk up or be a powerlifter.
For cardio, try powerwalking for 15 minutes on a flat surface. Flat surface minimizes injuries. Walk as fast as possible, don't run or jog, and try to beat your previous time. It's inefficient but that's the point. You'll get a lot of exercise and work the right muscles needed to walk or run fast.
If you want to do something less boring, run at top speed for about 50 meters, 10 reps. Give about 5 minutes between reps. If you start to go to slow, stop, you're done for the day.
If you just plain want to feel better, I'd say 80% of feeling good comes from diet. Basically, cut out high GI stuff like wheat, potatoes, rice. Cut out fructose. Get enough calories without those, but most of our bad modern diets come from too much french fries and soda. It's not even "fast food". Big Macs aren't bad, it's the side dish that's horrible. There are tons of good diets. All of them cut out that stuff.
I'd highly recommend doing some recordkeeping with the exercises you pick. After 1 week, 2 week, or a month, measure your progress. If you haven't made much progress within a month, ditch that routine. It's a good way to sift through all the crap you get from us and the rest of the net
To quote Eidolon's link:
[A sign that someone is trying to rip you off:] Extravagant claims of massive improvement in a short period of time with little or no effort. If it sounds too good to be true, guess what? It is.
I disagree with this. If it claims massive improvement in a short period of time, do it for a week, and record the results. I did sit ups for months with no improvement and a sore back. Then I switched to a 'get-abs-quick' routine and stood straight within a couple weeks. I'd say most of those get fit quick techniques aren't popular
because they sound too good to be true.