Where should I got for a vacation if I want green mountains, horseback riding, and maybe a lake nearby?

I'm going to leave on July 21st for about 4 days with my wife. We live in TX, but want to visit another state up North, where it's not very hot. We would prefer a place around mountains with green forests, and maybe a lake. We would also want to possibly go horse back riding, maybe fishing, but that's not a must. The more activities, the better. Any suggestions? Which state and city do you recommend? Thank you!