What to eat for energy for a extreme workout?

ok well im 40 and even though i was a fit boxer (not professional of course) because of work / laziness (i will admit its more lazy then work) and now a days i find it hard to find time to go to the gym because im a single father of 3 but when ever i do find time to just play with my kids like biking or basketball i get tired bc im out of shape so i bought insanity (the program) i can do it in the afternoon after work but what should a man at my age eat for energy for the workout? its an extreme 45 minute cardio session for those not familiar with insanity now i did know what to eat when i was younger for boxing but im not sure at my age (40 btw again) so please any good energy foods for a workout like that?