How important is medication vs behavioral therapy?

I'm new here, so if this has come up before, my apologies.

We have just self-diagnosed my husband with ADHD, after I read an article in a recent newspaper, which sent me to this site. We have no children but all the other 5 symptoms apply. He seems to have accepted this, since it's just so obvious, and to me, at least, it's a relief and offers some hope.

I would like to know how important it is to pursue a full medical diagnosis, via a physician, and how effective is medication, vs therapy? What I fear is that since my husband will be 60 next year, much of his behaviour is now deeply ingrained, and that medication isn't going to be a huge factor in changing how he operates. I've read some of the information here and see how medication can be worse than the cure!

Opinions on this? With great appreciation for your time and care.