Relationship

My husband and I are struggling and I am trying to do the things he likes. I really want to be able to do these things . It's not just to make him happy because I enjoy doing them but I don't know how to relax myself enough to let them go on for lo ger periods of time. Sorry for the tmi, my husband really likes blow job and I like doing them but I don'tnknow how to relax enough to give him one for longer then 5 or 10 minutes. Plus I also have terrible gag reflexes so that doesn't help. Anyone have advice on how to relax myself? I love my husband and he's always so stressed from work and I know this would help relax him.