Yoga has been around for a long time and there are many different styles, Ashtanga yoga for instance is quite strenuous and alot of it is done standing up whereas Sachananda yoga is more meditative and passive. Within each yoga style individual teachers will go about teaching their classes differently to one another so rather than being fixated on a particular style it is generally more useful to find a teacher who you feel comfortable with. Someone perhaps close to your own age and who is familiar with the type of health and fitness issues that you are subject to.
Where ever you learn yoga it is important that the teacher gives you useful one on one advice and feedback, if you are a nervous beginner all forgotten about at the back of a packed ashram, you will not progress as fast as you will in a smaller beginner-friendly class. It is even better still if you get one-on-one tuition in your own home, it will be more expensive but you will learn much faster. Home tuition is particularly useful if you cannot make it to class or are shy about learning infront of a class full of strangers, it is also good if you have the necessary discipline and motivation to do it by yourself.
If you need to learn yoga as a part of a large group to keep motivated and perhaps to make new friends, home tuition may be less attractive but whether you go solo or not, practising between lessons will get you the results you are looking for much faster. If you have had a yoga teacher highly recommended to you by someone whose judgement you trust it is a good starting point to find the right teacher. If such guidance is not available to you google where ever is closest and ask about attending casually until you are ready to make a longer term commitment.
The best stretching exercises in the world will not work if your body is too stiff to do them, getting a course of massages, acupuncture, osteopathy or chiropractic will give you a good head start to a more flexible, energised and calmer mind and body.
If you at first do not find a teacher you are comfortable with try another one, there may be a Pilates teacher with a strong background in yoga who may be worth trying. Not all yoga postures (asanas) are suitable for all people, if you have had neck problems for instance or you have a large body headstands might not be a good idea, if you have doubts about doing particular exercises discuss it with the teacher, there are usually several different ways to achieve better flexability using yoga.
Please be patient for results, years of neglect cannot be fixed in a few months. Once you start to get into the right stretching positions and learn to relax into them you will really start feeling the benefits. Compare how a stiff old body moves to a supple young body, it is flexibility that produced fluid motion.
I was once told by an older more experienced nurse that she found that people who had stiff bodies often lacked mental flexibility too…..refusing to do stretching exercise is a good example 🙂