Weightlifting is an amazing form of strength training and aught to be added into any routine but unless you've got a good budget to get weights brought to your home or can afford to go to the gym (when you do it consistently otherwise you're just wasting hard earned money), you can't carry weights everywhere with you and even if you could it be a pain in the ass in the long-run. There's always alternatives and that's one of the reasons I love to do bodyweight training; it's free, only thing being carried is you and there are thousands of things you can do just using your bodyweight.
The ultimate and most fun form of bodyweight training without question is Animal Exercise. Moving like a wild animal can be done in a variety of ways and almost all of them will whip your ass into shape in short periods of time. Its not easy just holding up your bodyweight but to move in awkward positions takes a great deal of strength. When you can move your whole body this way, you're not just building strength but developing loads of growth hormone that will help you stay young, lose weight, burn fat like butter to a hot pan and kick starts your metabolism which burns fat instead of storing it. Sure you can do your "kickboxing" dance follow along dvds or Tae Bo or Insanity Workouts but the truth is, as "great" those may be, you're developing a second rate self by doing something that requires you to work as hard or as long as the same people on the DVD at the same speed, same tempo and same workout over and over. You can't do the same as Animal Exercise.
Animal Exercises force you to use muscles not normally used in positions that can't be at the same speed or same exact positioning if you were to follow somebody. Everybody has a different structure and has to adjust otherwise if you go through the motions without regarding your own placement of the hands and feet and just follow, you can injure yourself or worse totally breaking something. The balancing is tough, the movement in some animal forms can be very difficult but with the right level of fitness and the way you pace yourself, you can progress a little quicker and bring in amazing results.
I have been doing this for nearly a decade and tested out well over 50 animal exercises from very beginner to high advanced and i'm telling you nothing gives me more thrills and makes me better conditioned than this form of strength training and overall development. Its both aerobic & Anaerobic, fast & slow, great to transition from one to the other, makes your brain work more which generates more nerve power, challenges your muscles more than any other form, upper and lower body are worked at the same time on most exercises & puts you into the driver seat by utilizing which exercises give you the greatest benefit. We are animals, we may have "better" intelligence than most animals but like the wild cats, the primates, the bears, the dolphin, the dogs, the birds we shed blood the same exact color. We may have evolved in 99.9% in most cases but we are nowhere near as strong or enduranced as they are and don't have anywhere near the same level of their abilities hence why we fear most of them. When you move like a wild animal, you become stronger than the average human, you form another level of intelligence, your energy takes in greater power to not just the muscles but the tendons, ligaments and joints down to the very crevasse of the bones. I have not found anything more athletic to do than this form of training.