First of all, what does it mean to be in "good shape." The answer is: it varies. If you've been involved in sports or regular physical exercise for several years, it's probably safe to start training with weighted clothes. However, if you are a complete novice, you will need the time to build the proper muscle, bone, tendon, and joint strength in order to be able to properly utilize these training tools.
You have some options when it comes to weighted clothing. You've got the classic wrist and ankle weights, then you've got things like weighted gloves, weighted belts, thigh weights, weighted shorts, weighted vests, upper-arm weights, and weighted shoes. You could virtually cover every square inch of your body in weights. That, obviously, is not a good idea. The best place to add weight during your training is your core, because it places less stress on your joints. However, if you wish to add weights to your limbs, do so in very small increments, such as 1/2 or 1/4lb, if possible. The best kinds of weighted clothing are generally made with little slots to add or remove weights in increments. Don't settle for the soft, sand-filled wrist or ankle weights, as they'll just get torn and spill out all over the place.
If you work hard and diligently, you will definitely be able to increase your strength. You can choose to wear your weights only when you train, only when you are not training, or all the time. For a second, imagine this scenario.
You weigh 150lbs and, through rigorous training, have worked your way up to wearing an additional 50lbs of weight at all times (1/3 of your total body weight). Think about the differences in your movement-- the power, the speed, the agility-- when, being used to weighing 200lbs, you all of a sudden weigh 150 again. It's a quite a staggering thought. However, as I said before, this is not something that is going to happen over night, or over a week, or a month... it will probably take years, especially if you are out of shape.
And you don't have to wear any weights at all. You can just train with your own bodyweight and do weightlifting workouts. It's whatever YOU want to do. Most of us aren't professional athletes, so the most important thing for us is to find a fitness regimen that we enjoy and keeps us healthy. That's what Real Anime Training is for me.
November was a little busy for me, but December should be a lot more productive for Real Anime Training. So, until next time, good luck and train hard!