First, to have soft skin you have to be born with it, like I was. My Grandmother had soft skin. My Mother has soft skin. It has carried through the generations, and both my sister and I have been blessed with extremely soft skin. I don’t know about my brother’s skin; I never touch him. Boys are gross.
Second, how to maintain soft skin: like all skin, soft skin must be well cared for. Don’t use soap, don’t scrub too hard. Exfoliate. Moisturize to keep your skin supple and youthful for as long as possible, because youth is valued in our culture above all else. Wear sunscreen. Always.
Youth is valued. 
No sunscreen = lizard skin later
Third, if your soft skin is also sensitive skin, it needs additional maintenance. Sensitive skin is vulnerable to the elements and can be harmed by them. Sensitive skin can be taken care of, but only with protection from those elements. The “elements” are those things that are bad for you: sunlight between the hours of 10:00 and 4:00, also commonly known as the daytime. Many things are bad for sensitive skin: Sunshine. Cigarettes. Criticism. Too many jokes as the youngest child of four.
If, through no fault of your own, your sensitive skin is damaged as a result of being “too sensitive,” you must take care of it more aggressively. Sensitive skin must be made stronger. Sensitive skin must, with copious amounts of vitamin C, sunscreen (but not sun), tears, and, of course, laughter–and cruelty– sensitive skin must be transformed into thicker skin. Through the correct regimen, of course.
Over the years, I have succeeded in having thicker skin, by surrounding myself with people who tease me until I laugh, sometimes until I cry. If the process hurts, I repeat, because that means the regimen is working. Beauty takes pain, and you don’t just develop thicker skin over night. It takes years, and it takes practice.
If you succeed in having thicker skin, like I did, as a result you get to have even more experiences, a richer life. Then, if your skin is thickened enough, you can, if desired, proceed to the next level of skin care. In other words, you can develop what has been prescribed for you by many others over the years: tougher skin.
It takes years to grow a thicker skin… 
It takes even more years for tougher skin…
Beauty takes pain, and you don’t just develop thicker skin overnight.
I have skillfully developed thicker skin over the years, but my Clinique counter technicians have not, in fact, given me the go-ahead to treat my thicker skin with newer products. In other words, I now have thicker skin, but I still don’t have tougher skin. And, because I have been so diligent about sunscreen my whole life, I might never get it. I can keep trying, though, and because skin care is a life-long regimen, I might get there one day…if I want to…which I don’t.
Sensitive skin is one thing, thicker skin is another. I’m just not convinced that I need to have tougher skin. If I were to have tougher skin, what does that say about me and who I am as a person? Why would I need–or want– a tougher skin? Who would I be spending time with, and for what reason do I need to have it? Why would I be spending time with that terrible person? I love my husband, and I know I don’t need tougher skin to spend time with him! He’s lovely. My friends and family, too. For the most part.
Sensitive skin I was born with. Thicker skin I developed so I could better function in the world and not burst into tears at the drop of a hat. But tougher skin? I don’t need it. I don’t want it. I’ll just keep my sensitive, now thicker skin, thanks. Being covered in tougher skin? Nope, not for me. Those beautiful, porcelain faced Clinique technicians can keep their free make-up bag and their mascara, too. I don’t wear mascara anymore.