Re: relaxing during technique - how?
Always out of breath suggests physical fitness or circulation problems depending on age and condition. Back in the day I could go for hours at "aikido practice pace". Now I have to rest frequently. In the intervening time I have gained weight and I drive a car to and from what little training I do, rather than ride a bike or run.
All of the aikido training hints above can help. Additional low-intensity exercise can help (depending on how far you live from work or training, can you bicycle there?). A quick visit to the MD to check your ticker might sound over the top but depending on age and history it might help, too.
In addition to that - a lot of aikido training can help, too, simply by training and training (as facile as that sounds) your body and nervous system will learn how to move in a 'relaxed' fashion.