Changing your last name to your husband's or adding our husband's to yours, isn't old fashioned. It is entirely personal preference and you should do it if you want. One friend couldn't wait to change her last name because she was tired of her last name starting with a "W" and having to wait last for everything. When she had the chance to move up the alphabet to "C" she went for it.
If you are excited about changing your last name but nervous about all the different steps, the following infographic should help! Plus you can use it as a checklist so you remember to change your reward cards too!