Okay guys I think I'll crack on a little bit with some general fitness advice and a small routine for those who have major time constraints.
Conditioning
That's the word for the day folks! Parkour is a discipline, it is both a physical activity and a lifestyle. In order to be effective at parkour you need to effectively manage your life.
So you must condition your mind, body and spirit. I can only give you advice in how to condition your body, the other two are down to yourselves.
In order to effectively do the physcial act of parkour you need to ensure your body is ready for it. You need to shape your body into the most efficient tool it can be for the job. So it's not all tricks and big jumps and stunts. You need to routinely put your body under physical stress and build it up for the task.
Here I'll design a basic workout that includes no parkour at all. But will hopefully give your body a general wakeup call and maintain and build the core muscles strengths needed for parkour.
Warm Up
Always warm your body up, not only does it increase blood flow to the muscles but it increases the effectiveness of the synovial fluid in your joints and the elasticity of your muscles. A good warm up can also put you in the right frame of mind for training. It prevents injury and readies your body for the activities ahead. This is a general warm up that should get you ready for the training ahead.
[]Jog on the spot (2 mins)
[]Bouncing from left foot to right foot (2 mins)
[]Bouncing forward and back alternating lead foot and throwing light soft jabs (2 mins)
[]Stretches (all hold for at least 30 seconds)
[]Calf Stretches (stand with one knee bent and other thrust straight back behind you and feel pull on calf muscle [gastrocnemus]).
[]Quad stretches (Grab foot with both and hands and pull up to your backside as far as possible, for more stretch try to thrust hips forward)
[]Hamstring stretches (stand feet should width apart, grab as close to your ankles as possible and pull yourself down)
[]Hip Twists (twist on the spot changing every so often)
[]Arm swings forward and back
[]Deltoid stretch (pull arm across body and put pressure on elbow)
[]Tricep stretch (put arm down back and push back with other arm)
[]Wrist rotations (rotate wrists around in all directions)
And that should do it! Now for the hard work.
Work Out
The workout itself is designed to use only your body and possibly a chinning bar (or park rail or even a door frame if it'll hold your weight). It should work every major muscle group that you'll use in Parkour. Do these exercises in your own time, but aim to do them in sets of either 10 or 5 without stopping. Take small breaks of half a minute to a minute between each separate exercise to catch a quick breather and replenish the oxygen in your system.
[]Push Ups (10 normal 10 wide arm 5 close hand and 5 on finger tips)
[]Sit Ups (10 normal 10 with your legs in the air and 10 with legs out straight 12 inches off the floor then coming in to crunch, without your legs touching the floor)
[]Squats (30)
[]Burpees (10 Squat thrust to standing jump then back down is 1)
[]Chin ups (30 if no bar or door frame XD use a chair that is sturdy, lie on your back and pull yourself up to it in what should look like an inverted push up.)
[]Straight jumps (20 squat down and jump as a high as possible, try to make your landing as quiet as possible.)
[*]Crocodile walk (20 meters or more if possible and if space allows for it. If not do 25 wide arm pushups)
Then jog (for 10 mins and build up time as you progress, aim to be able to keep moving for about 30 mins)
That's the hard stuff, by now your body should feel a physical wreck and you'll need to think about your warm down.
Warm Down
Probably the most important bit. This will ensure your muscles don't tighten right up after a workout and it will give your body time to return to normal. It is essential you don't miss this out of your training.
And there you have it, some light conditioning. It's not easy and it should challenge all fitness levels, but take it and adapt it to yourself. Personally, I do a load more and with the benefit of equipment to help, but that's just me, I have access to a gym, for those that don't here you go.
Lifestyle
For you albac, I noticed you mentioned about why you want to train and such so here's a small piece for you.
The stretching shouldn't be over done, it is important, but just 30 seconds during a warm up should be fine. As your muscles become warmer they become more elastic anyway (up to 80% more elastic). So you'll gain flexibility over time, the times stay the same you just stretch farther each time.
Your body builds fat because it is taking in more calories in a day than it needs. There are no ifs and buts even in regards to metabolism and such. Just don't take in as much in the day. Your mind is making you eat routinely but it doesn't necessarily need what's going in. To lose that extra bit, use more calories in the day than you consume, over time it will go. But not over night.
Stamina is built and it is usually the thing that people fail on the most. It is hard to have your resolve turned to dust by a long run. Just build up slowly over time and don't over do it. If you feel you need to stop, try not to stop, just slow down, even if it is to a brisk walk.
Your muscles will balance properly from use. Exercise the whole body and all of it will be in tune, plus you will learn instinctively how your body wants to move and such.
As for time management I can't help. 4 hours sleep is drastically unhealthy though. You need to ensure you rest more. Especially if you start training since your body recovers most when it sleeps. Plus lack of sleep can affect loads of things. Like I personally need at least 8 hours or I start to run a higher risk of seizure since I'm epileptic and my sleep affects it. As for your job I don't know what to say. We all need to put food on the table and pay the rent mate, so work should come first. Just make sure your not spending your life there unnecessarily and try to use the rest of your time as productively as possible (I used to do pushups and situps in the lab break times at my old work XD).
So there you go guys. Hope that helps you all a little bit!