Hello again QBaby,
Don't worry - you can't do anything beyond what you're ready for. Same goes for things as mundane as for example jogging, swimming lengths or learning a new language! You capacity will develop and accumulate at its own pace. I think what Claire says is very true - go easy - start with short practices of 5 or 10 minutes maximum and see how it goes. I initially tried to do the full physical exercises along with the video every night, but it was simply too much for my arms and legs - so I decreased the duration and have been building it back up ever since - I find that my strength has been building gradually ever since.
Regarding reverse breathing - if you find you are straining or it feels uncomfortable - stop, seek more advice on ways to change your technique and in the meantime stick with what feels most relaxing. (there are some good tips on reverse breathing on this site if you look up the archive, but remember - using the technique at this introductory stage is less important than moving towards a state of deep relaxation). Simply let go and keep it simple - it's all about being gentle. I, in fact, find the meditation practice most relaxing and effective when I begin to achieve a state where it feels like the breathing is almost "doing itself" - almost as if the energy movement and the breathing happen as one. I usually find that I reach this state easiest, when I am not preoccupied with technique, but focus more on the energy sensations/visualisations. It's almost like a feeling of surrendering to what is already going on, rather than trying to force anything.
If there are any ways in which you could help yourself physically (though again this is not at all necessary and wouldn't be possible anyway for people with severely debilitating physical conditions), you could attend some introductory Tai Chi or Yoga sessions in your local area to improve your posture. I recently began a very basic Tai Chi class and found that it greatly improved my back strength, which in turn, helped with the physical SFQ exercises. I would still hold, however, that the most powerful practice is the training of the mind (in itself a specific form of Yoga and Qigong), so I'm only suggesting these possibilities if you feel you would like to do more to develop yourself in support of SFQ practice. Sometimes this can actually help with the development of your mind anyway as you feel you are actually doing something practical, with the tangible support of people you can meet in person - plus it can only benefit the SFQ practice. (Make sure you get a good Yoga or Tai Chi teacher though, who isn't into the western "aerobicising" of what are much more complex disciplines, with deeper objectives than trying to lose weight and being able to impressively wrap your legs around your head!)
Again, good luck with it all and keep in touch!
best wishes
Ingrid
