Ok, well thanks much for the advice. However I was hoping for more because they are well beyond the normal range in lack of courage and I feel something extra should be done. I don't necessarily want them to be all around tough guys, I just want them to be braver than girls half their age. They are becoming very good at behaving like tough guys, (in order to get the attention of girls and respect of their friends), but when anything that calls for any remote amount of bravery, they cower and run. It's embarrassing them and I want to teach them how to overcome.. or at least get them to even think about not running away from fear.
Right now they instantly run away without thinking and seem to prefer feeling shameful to facing the danger.
My advice, take it in smaller strides. It seems (from your post) that you want them to grow up to be these tough guys that no one will mess with but unfortunately that just isn't everyone. My kids were once afraid of bugs, but by acting like they were no big deal, saying how cute they were, but not forcing them to touch them, they slowly - but surely, came around and now gross me out with the bugs that they do touch. On your walks, don't force them to come all the way in, instead, take it in steps, maybe one day they'll just go in and out, then next, take a few steps in then out... have them lead and set the pace of what they will or won't do.
Shaming has the opposite effect, it will make it worse.... If you make a big deal out of it, it will be a big deal to them (in a negative way).
Sometimes we forget that our kids are individuals and that just because we like to do certain things doesn't mean they will. Try getting your older nephew to go running with you (it's a physical activity), maybe start on a track then in the woods (baby steps).
If you are able to get him to try new foods let me know... I'm still working on that one with mine!
If it's ok, I'll throw some background in. The kids mother left them when they were 2 and 4 and I moved in shortly after. She moved to Germany and sends gifts and occasionally calls them when they visit their grandmother/her mother. Their father is the kind of guy that feels they'll grow out of anything and for the most parts he accommodates. Like they're afraid of the dark and so he has their bedrooms in near daylight all night long. They also have their grandmother on our side that lets them walk all over her and throws gallons of her mothering instinct on every little scrape.
I have taken the crazy uncle role so to speak. I feel it's my job to get them to do things out of their routine and I try and take this job seriously. I've also got a reputation in the neighborhood and other parents reluctantly let me take their kids on trips to the creek and stuff and I've been known to get them dirty and wet and exhausted.
Things I've tried so far: One way I can get them to do brave things takes forever and is taxing to say the least. I had the younger one attempting to ride his skateboard down a ramp. It took about 45 minutes of pep talk, he finally did it and I jumped for joy, but since it was such an easy task he didn't seem to get much reward. I have to admit that I've also tried shaming them into doing things. This I don't do anymore because all they do is feel shameful. The thought that if they take the risk to make the shame go away never even enters their minds. They just ride out the shame until I give up.
They love going on trips with me and look forward to our long walks on the weekends and I'm sure this makes them feel adventurous, but simple things like getting them to explore down a ravine, they stay on the road and just look shameful. They get a little braver if their friends do it, but not much. I can pretty much get their friends to do anything, but I keep that limited because they're not my kids, haha.
The only good side of this is that doing something illegal is near unthinkable to them. I, at this point though, would be ecstatic if I heard they stole a car.