First of all, you haven't done anything wrong. Do not feel disgusting or upset. Smiling and walking away is common for younger women who are embarrassed or feel awkward because of a situation, it's not something to be upset at in the slightest.
If you had heard him then maybe you could have conducted yourself better, but you haven't done anything. Smiling is not an invitation for him to do anything, it's called being polite. If he says anything again, I'd simply ignore it or put him right.
Just say no. Secondly, don't let this stop you running if it is something you are passionate about or even just enjoy. Maybe you could pick a new route to run for a while if it bothers you so much that you don't want to see him again.
Tell your parents, they won't be upset at you, they may be able to offer you advice on the situation which will help more than I can because they know you! Your clothing is not an invitation for people to react to you like that and you should be allowed to wear what you wish (to a certain degree of course, there may be children around!). Maybe you could see if you could find a running partner?
Safety in numbers right? I'm not suggesting this man will do anything, but it could help you run if you are more confident that you are safe and can concentrate on your exercise rather than worrying about this situation. Although it is possibly the last thing you want to hear while running.
Stop taking this as such an insult. It was vulgar, and definitely not something you want to hear from a stranger, especially if it makes you feel disgusting. It is however a compliment in its own way.
Just think of if he has said, you are a really gorgeous young woman. I know it is different, but don't let this harm your confidence. You can't decide what that man does but you can decide how you take it.
He finds you attractive, but cannot control himself in an appropriate way. Lastly, your parents are your parents. Just because you are 18 does not mean you can't ask them for help.
They will still want to be there for you and you should still be able to ask them for help. Most of the time sorting things by yourself is fine. But advice, parents can be brilliant with advice.
They have probably lived through experiencesl ike these or know people who have dealt with them before! Ask away, stay safe and keep enjoying your running!
You are WiLDLY over-reacting. At that age, chances are this man has mild dementia and has lost the ability to know what you can say out loud and what you should keep inside your head. There is absolutely NO need for you to do anything except keep running.
He's not going to run after you, is he, or jump at you with a knife and drag you behind a hedge! Smile or ignore him, just as you please, and run past. OF COURSE you didn't "bring it on yourself".
Please stop obsessing about this. These things happen, and on a scale of worrying and frightening events of 1 - 10, I'd rate it at maybe 2. You are in no danger, you don't "need help", and you're over-dramatiizing a very ordinary incident.
EDIT to add @Mildred: people with dementia are not "stupid". Rather, they have lost the ability to distinguish between thinking something, and saying it out loud.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.