How to keep energy levels up?

calories

Calories. Check... already on the list from above.

Maybe a quick walk? When it's pretty outside I'll walk around my office building to get the blood flowing a bit, that usually energizes me.

make sure the sport drinks you're using aren't primarily sugar.  Go with caffeine instead, coffee if you're a coffee person, or better yet green tea.

I really like FRS

http://www.frs.com/

I'm in the same boat as you.  Live in Chicago, work 50+ hours a week, go to school, and train for triathlon.  Are you sure you're getting enough sleep?  That's my main problem so I know it's hard to get 8 (even 7) hours of sleep every night.  I've been lacking a lot of sleep lately getting about 4hrs for the past 5 nights or so.  Just yesterday I went for a 30mi bike and was more tired than usual after 20mi and had a hard time finishing.  I got home, stretched, showered, ate, and knocked out at 7pm.  I woke up at 4am for work and felt pretty good for the rest of the day (I also had my cup of coffee, of course).  But, if you're good on sleep I don't know what to tell you.  I generally stay away from energy drinks and stick to coffee especially since I'm an enthusiast...you should try Intelligentsia Coffee by the way if you never have, they're in Chicago . (not affiliated in any way!)
Good luck!

How long have you been traiing?
Overtraining?
Just trying to do too much?

x2-- and I don't do caffeine. Intelligentsia is delicious stuff: even their 'unleaded' versions!

WATER

I do not drink coffe or sports drinks, so water it is.  I have been taking those Emergen C packets for minerals supplements once or twice a day.  That is about it. 

If you overhaul your diet and stay away from caffiene, table sugar, and processed foods, you will notice the consistency of your blood sugar level will keep you from crashing throughout the day. I also notice that I don't need as many snax during those longer bike rides cuz I'm not crashing during it. I use to feel that 40-45 minute need for a gel. Not anymore. Just have to suffer through the 2 week headache, then all will be good. A good book to understand this better is Phillip Maffetone's In Fitness and In Health. I bought it from Amazon. Booked changed my life, not only my training. You can switch your sport drink to Suceed brand products and use Chocolate #9 gels to get completely away from the sugar as far as your training goes.....Just trying to pass along some info that drastically helped me.

I have this problem on occasions not as much now since i've improved my sleeping patterns and increased my water intake more during the day to stop from becoming dehydrated, as this can cause tiredness. I am a shift worker that works 12hrs days and nights 60 hrs a week in a hot enviroment and hydration has been drilled into us lately due to a new health and wellbeing program my company has introduced. I know it sounds to simple but it definately has worked for me.

Thanks for the advice... I have to say that I stay properly hydrated... The only energy drinks I have are sugar free small red bulls... I dont crash... I have been training for probably 10 years... haha... but this year I have been going for 3 months already. I just have to say that I end up beat. My legs will feel heavy some days and other days I will be perfect. The bad thing about my work is that I spend all of my time on my feet, going up and down ladders and carrying heavy stuff. If I dont get my workout in before I feel that my legs and feet can not handle it.

Sorry, I guess I should post I'm also in Chicago, this is a valuable credential!

Seriously though, quality calories and proper rest.  I have never really eaten sweets so I usually don't deal with sugar crashes.  I rarely ingest caffeine, but when I do its tea or sugar free red bull (the regular stuff is too sweet).

You mention your legs are hurting.  Try throwing bananas into your diet in some quantity. I always found potassium (read: bananas) helped me after heavy squats, and I started doing it after long rides too.  If you're in the city, I highly recommend the trek to Stanley's for your fruit. If not, dominick's etc will do.

mmmm LOVE FRS! Just got some in and have been a happy camper since!