I am significantly older than you at 48, but I had my melanoma diagnosed and removed at 46. Luckily, I was staged at 1B, but I still live with some concern about making my 10 year anniversary.
As for you, there are more risk factors than simply living or not living a healthy life. Those individuals who have fair skin are at higher risk. (Though that is not to say those with darker complexions cannot get melanoma - Bob Marley died from Melanoma.) Red/Blond haired people have a higher risk. Those individuals with a lot of moles, especially those that change have a higher risk. If there is a blood relative who has had melanoma, your risk is significantly increased and you should be having regular skin checks.
Sun exposure for everyone places individuals at a higher risk, especially without sun protection. Putting lotion after exposure to the sun is supposed to do...what? Moisten the skin, yes, but protect against melanoma? Yeah, I don't think so. And tanning beds? They are as bad as being in the sun, doesn't matter the amount of time. Any dermatologist who specializes in melanoma (and not botox injections) will tell you that.
It seems you are a man? So that would mean your risk would be higher on the torso and arms - just something to keep in mind. And something else to keep in mind - melanoma has NO CURE! There are treatments, yes, but NO CURE. And once melanoma reaches stage 4, unless you are very, very lucky, the prognosis is 6 to 9 months. I've known many people who have fought this disease and ultimately died, most in their late 20s and early 30s. There is a reason why late stage melanoma patients call this cancer the "beast." It is extremely aggressive and something to take very seriously.
But, enough lecture. I'm not sure if you'll listen anyway. To answer your questions:
1. how much were in the sun from your teens to mod 20's?
A LOT! I was a typical Southern California teenager - I practically lived at the beach in the summer. The most important thing between June to September was getting that "perfect tan." I mean, one just could NOT go back to school in September unless one was a golden shade of tan! Back then (the 70s) we truly didn't care if we had to "die for that perfect tan." It all seemed so important then.
In my 20s the pursuit of the tan continued. I was either at the beach or at the pool. And my vacations were in places like Hawaii, Cancun, Mexico, or Jamaica. If it involved water and sun, I was there!
2. did you use any SPF protection?
Now, why would I do that? Seriously, we all wanted to be TAN!!! Okay, you have to understand the times I was living in. I was a teen in the 70s. This was a time of not only tanning lotion but tanning OIL! If that didn't work, we would pour baby oil on our bodies. We wanted tan, and we wanted it fast. Lotions didn't cut it, oil was the only thing that worked. I don't even know if sun screen was sold back then. It must have been, but we didn't think about, know about, certainly didn't buy it.
When I was in my 20s, you are talking about the 80s. Sun protection was just beginning to become something people were becoming aware of. But, heck! C'mon! You're 22, you know how it is - you're gonna live forever, right? And besides, by the time you have to start worrying about getting old and all that stuff, they'll have a cure or something for it. Besides, what're the odds that'll YOU will get that? I mean, really. Yeah. Well, that's where my mind was at when I was 22 as well.
3. Is there skin cancer in your family?
What type? Melanoma? No, I have the dubious honor of being the first. How lovely. My mother was diagnosed (after me) with basal cell cancer, which she had removed. I wish I would have been as lucky as my mother.
4. Do you eat healthy?(no trans fat,butter & other unhealthy foods)
Now? Or when I was younger? Or all my life? When I was a teen, I ate as all teen pretty much do. In my 20s, I did the healthy thing (with the exception of the sun thing): practically lived at the gym, very active, ate healthy. In my 30s life got busy and chaotic - my father passed away and I developed a serious health problem. Eating healthy became less of a priority for me. In my 40s (now) with aging and the health problem in the 30s being resolved, I've once again focused on my overall health and a major part of that what I eat. I'm not obsessive about it like I was in my 20s, but I'm cautious that what I put into my body does my body good.
5. Did/do you exercise a lot?
Well, I think I sort of covered that, but throughout my teens/20s I was very active, yes. With the health problems I had in my 30s (vertigo problems), it was difficult to impossible to be very active. However, now that has been resolved, I have once again become active, and enjoy being so. I don't do what I did when I was 20, naturally. But I fitness walk (participate in 5ks, with the hope of walking a half-marathon soon), hike, yoga, bowl, and will occasionally hop on the old bike!
6. Any advice for me?
Oh, lots of advice!

However, I do mean well. I have read so many people's stories and have gotten to know a fair number of people who have suffered and died from melanoma. This is actually a fairly easy cancer to protect oneself from. I know how hard it can be to resist the temptation that society places on people - especially young people - to have that "look." Especially here in So Cal, where looks matter so much. I can't tell you how many times in the past year people have told me I should "get some color." And these are people who KNOW I've had melanoma! You are young, you are healthy, you have so much life ahead of you. Please, don't put any of this at risk just for the sake of making your skin a few shades darker. If you were to develop melanoma, what cost would that be to you? And you do realize you can develop melanoma in places you can't see easily, right? The scalp, private areas, soles of the feet? These are areas where melanoma can spread and you have no idea before it's too late.
Enjoy your life with all the energy you have! But protect yourself as well. It's so simple to do, and has big payoffs in the end. Besides, you speak of being health conscious, but have seen people who have been exposed to the sun a lot when they are older? It's not always pretty! Take care of the body you have now in ALL ways, and it will take care of you later!