Yes, any amount of progress is a good start I say. Its best to do it in the early mornings, like 9 or 10 am, that way its relatively warm out since the sun is still rising. Not too hot and not too cold.
You'll slowly make some good progress if you keep up with it daily, but start doing it like three times a week. When you get used to it, keep upgrading a day until you can go a whole week without getting sore or worn out.
Well, alright, but don't starve yourself, like, go for a morning jog every day, that'll help you burn some calories, or go to your local gym for some assistance there.
Do they consider you too skinny? I consider unhealthy skinniness is anorexic skinny, you know, where you can see the person's ribs and stuff. But, if the weight bothers you, thats all that matters, nobody else's thoughts.
Did you like eat a lot of junk foods or something? Or neglect a couple days of exercise? To be honest, my weight doesn't bother me, I've been a big kid all my life and got picked on for it. But now I couldn't care less about what others think of me as long as I'm happy with who I am.
I've messed up more than you though.. thanks to my idiotic brain, I think its because my dad woke me up early today and I didn't get enough sleep. Now my brain is making me do the wrong stuff and its gonna make me so mad that I just leave and go to bed. xD