In the later portion of my training session, I seem to lose a lot of energy and feel very weak especially during heavy bag work. My cardio seems to hold up during my sessions but maintaining strength and explosiveness without getting weak and shaky needs a lot of work. I know strength and power are developed over time but maybe I need to address my diet. It isn't very strict, but I do try to get at least 1 gram of protein per 1 pound of bodyweight (is that generally a good amount by the way?), plenty of calories, and enough fruits, veggies, and greek yogurt (I'm addicted to the cherry flavor by the way lol). Would I have to increase some of those perhaps?
Yup 1-1.5grams of Protein per pound of body weight is ideal!
1)The first thing you should adjust to help give you the energy you need for a full workout is your Diet. I'm not sure where you are at as far as body composition goes (want to lose fat? Maintain around your current weight while putting on lean muscle mass? or bulk up?).
Anyways, use the Calorie calculator below to figure out how many Calories your body needs on average to maintain your current weight. If you want to lose weight, subtract 500 calories from that #, keep it the same if you want to maintain your current weight, or add 500 calories if you want to put on a little weight/mass.
http://www.freedieting.com/tools/calorie_calculator.htm
After you decide on your daily Calorie intake, use the Nutrient Calculator below to get your MacroNutrients aka Macros (Lets you control how many grams of Carbs, Protein, Fat you get your calories from). Set your Protein % to make it so you're getting 1-1.5g per lbs, then decide on your Carbs & Fats.
http://www.freedieting.com/tools/nutrient_calculator.htm
Get some good carb dominant food in you 1-2hours before training.
2) Rest: Are you getting 8+ hours sleep every night? Also, try out a 30-1hr nap during the day to see if it helps
3) Drinking enough water? 1 gallon per day. Drinking enough water during training?
4) Stamina: It will get better with time, but you may also try some stamina building exercises if you have the free time. Maybe more shadow boxing or heavy bag work on non training days?
5) Supplements: Are you taking Caffeine? If yes, how many mg and when do you take it? If you aren't taking Caffeine and are not sensitive to it, maybe you should see if it helps.
Creatine Monohydrate, Beta Alanine, Citrulline Malate: Performance enhancing supplements listed in order of proven results through scientific studies. I just ordered Ndure from TrueNutrition which has 250mg Caffeine, 5g Creatine Monohydrate, 4g Beta Alanine, and 1.5g Citrulline Malate per serving. Hasn't been shipped yet, but it seems like a solid mix. (Not affiliated with that company in any way)
Ndure
http://www.truenutrition.com/p-1177-ndure-32-servings.aspx?vid=1219