I'll give you the same advice everyone else is, but word it slightly differently, because thinking this way really helped me: Be OK in your own vulnerability.
'Toughness' implies some sort of everything-proof shield that you expose to different stimulus to gain 'immunity' from it. I've seen advice that follows this line of thought: eg you quit bathing for a week and become 'immune' to some specific social judgements, you go to some extreme sport to be 'immune' from the fear associated with it, etc.
The problem with the above is it starts feeding into this weird 'detached, tough guy' persona that cracks as soon as you realize something has gotten to you. You think "oh no, this thing isn't one of the many things I'm immune from!" and will try to counter it with some sort of extreme, tough-guy exposure. Until the next thing gets to you. Etc.
Rather than doing that, you should realize what creates the toughness in the first place: it's being vulnerable (physically, emotionally, intellectually, etc.) and realizing it's an OK state to be in. Even if you're in a vulnerable state, you've "got it", you'll make it out of it, it's not the end of the world, etc.
Now, you can practice this by putting yourself into vulnerable states and showing yourself that you survive them (but you have to remember to let yourself generalize so you don't get stuck in the 'tough guy' mentality I described above) OR you can explore the concept of vulnerability in general and learn to be OK with it. I recommend the latter :)
To that end, I really liked "the gifts of imperfection".