Training in the summer?

WOW!!! It is hot and stuffy where I am lol, plus I nearly fainted whilst training (boxing)... I had to stop, It was like 15min in the workout... I hate summer. I'm thinking of making a summer routine up, so light workouts ect... I do karate aswell... I really don't feel motivated in the summer :(... cause of the heat stopping me to do my workouts, well rarely it does. what should I do ?