I did 6 months in a campervan about 4 years ago, followed by about 5 months the year after. I gave up my job and my house and it's the best thing I've ever done. Even with the degree of mobility afforded by a house on wheels, 6 months was only enough to scratch the surface. 6 years wouldn't be enough
Similar to you, it was something I felt I had to do. I can't comment on whether it's a good idea to do it on foot if you've never done any backpacking before, but if you're in a similar frame of mind to where I was I would imagine that you're really not concerned about that aspect of it, and you're probably right not to be. It was a wonderful and worthwhile thing so here's a few of my experiences as something for you to think about.
Don't go with too much of a plan, it just puts pressure on you. Follow your instincts and follow your heart and you'll really feel the freedom.
Prepare to be lonely. The solitude will help with the clearing of the mind for sure but try to plan some visits to decent hostelries from time to time to reconnect with humans
I went a little stir crazy after an entire week of appalling weather pretty much confined me to the van and my own company but a Saturday at the Clachaig Inn and some live music sorted me out
The Highlands get under your skin. Be prepared to keep coming back for more.
You will come back fitter - physically and mentally - than you have ever been and you will want to stay that way. You can't bring the Highlands home with you but you can bring the memories (get a camera) and the attitude.
Go for it. I wish I could do it again for the first time.