what you're experiencing is probably whats called post acute withdrawal syndrome, or PAWS. most people who use opiates for a short period of time will experience acute withdrawal, but feel completely back to normal after a couple weeks. those who use opiates for a more extended period of time, even at a moderate dose, will experience some combination of PAWS symptoms after their acute withdrawal has subsided. the symptoms are usually anxiety, depression, lethargy, and insomnia. the lack of energy you described is most likely the post acute withdrawal. it can be a real bitch. any time you take a drug that directly or indirectly (indirectly in the case of opioids) increases dopamine release or modulation, your brain will grow accustomed to it. motivation is largely modulated by agonism of dopamine receptors. dopamine is what motivates us to move, eat, have sex, etc. when you introduce extra dopamine, the brain becomes wired to motivate you to seek out the source of that extra dopamine. this is a large part of both physical and psychological dependence. when you get off the drug, your brain is hardly motivated to move, eat, have sex, etc because these actions provide less dopamine than the drug does. this is the source of cravings. you are barely motivated to do virtually anything than get drugs. you feel like you could barely walk to the kitchen to make yourself some food. but i'd be willing to bet that if someone said they'd give you a handful of pills if you walked 10 miles to their house, you'd have all the energy in the world to get down there. and you'd be walking at a nice brisk pace. it's just a matter of waiting it out. the wait will be a lot longer if you sit around and don't do anything though. even though you don't feel motivated to do anything, you gotta force yourself to do it. this will release moderate amounts of dopamine, which over time will reset the dopamine threshold so you begin to feel pleasure from the small things again. that, in turn, will reset your motivation, which will return your energy levels to normal. when i was in rehab, they forced us to do all kinds of chores and fun activities. we didn't wanna go to the fucking beach, we wanted to get loaded. but after a while, your brain begins to adapt and you begin to feel like a normal person again. in all my experiences trying to kick opiates by myself, my withdrawals lasted much longer than they did in rehab. they lasted so long that i would consistently use before they even ended. for that reason, i failed at every attempt until i ended up in rehab. it was because i would lie in a bed in a hotel room, thinking i could just wait it out like a flu or something. it's your brain that's sick, so you gotta start using your brain again. read, write, draw, socialize, eat, masturbate, watch movies, exercise, etc etc. i found myself listening to music a lot and walking around in circles when i couldn't sleep. eventually, my sexual function returned to normal and i found myself motivated to have sex with my girlfriend for once. when i was on heroin, i would have sex with her just because she wanted to, and i liked to see how long i could go without having an orgasm because heroin numbed my dick up so much. it felt great to be motivated to do normal things again. so basically, my point is that your energy will return to normal if you a) obviously don't take any drugs and b) move around a lot, use your brain, and go through all the activities of normal living. if you sit around, mope, and pity yourself, your energy will take much longer to regenerate. in fact, i think your energy won't regenerate at all until you are forced to get up and move around. i strongly recommend physical exercise. also, a big part of rehabilitation treatment is diet and supplementation. you should get an amino acid supplement, specifically one with all of the essential amino acids. not a bodybuilding one, but the pill form which contains all of the amino acids and not just the androgenic ones. every neurotransmitter in your brain is synthesized from amino acids. every enzyme in your brain is synthesized from amino acids. so if you're not getting amino acids, your brain won't recover period. you get them from your diet, but a lot of them only exist in considerable quantities in certain foods. so unless you're eating a really diverse, healthy diet, i recommend the amino supplement. i also took melatonin and something called picomilon. picomilon is a molecule made by attaching GABA (gamma-amino-butyric acid), an inhibitory neurotransmitter that calms you down, to niacin, an essential vitamin used to treat high cholesterol and anxiety. GABA by itself does not cross the blood brain barrier, so getting a GABA supplement is completely useless. don't even bother. but basically when you're strung out on opiates, your brain stops producing and releasing GABA. when you detox, your brain struggles to replenish its GABA stores. this is one reason why withdrawal causes anxiety. niacin is a co-enzyme or precursor to co-enzymes in over a hundred different reactions in the body and brain. niacin is used for detox because it increases liver function, and increases the rate at which your body and brain repair. it can make a huge difference in detox, because no matter how many other supplements you take and how much exercise, mental and physical, you undertake, your body won't use the supplements to repair the alterations in neurotransmitter function unless you are providing it with plenty of niacin.
so in summary, here's a good regimen for you.
*exercise physically at least an hour daily, including resistance training at least twice a week
*exercise mentally at least three hours daily, however you see fit. i found going through my calculus book to be both invigorating and distracting. i would barely feel my lethargy and anxiety when i focused my mind on something. and i really think that using your brain, no matter how hard it is, forms new connections that eventually overwrite the drug-related connections. and this kind of exercise stimulates your brain to use the amino acids to regenerate, in the same way physical exercise stimulates your muscles to repair and grow. the brain is basically a muscle.
*take all 21 essential amino acids daily. no more than the recommended dose though, which could cause liver damage.
*take picomilon if you can find it.
*take niacin. don't take the sustained release formulation, as this can damage your liver and bowels. you should take the instant release form if you can. read the label to make sure it is niacin (nicotinic acid) and not niacinamide, which is half as effective. remember that niacin causes your blood vessels to dilate, which induces a flushing sensation. your face will be flushed - this does not indicate a dangerous reaction. it is very safe and impossible to overdose on unless you take thousands of times the normal dose. if you can't find regular, straight up niacin, get inositol hexanicotinate. it will likely be labeled as niacin, but on the back it will say inositol hexanicotinate. this is an esther of inositol and 6 niacin molecules, it's just as good as regular niacin and it doesn't cause your skin to flush. you want to take at least 1,000mg of niacin a day. i take 3,000mg a day, but i used to take 5,000. you want to space out your dosages. for example, i take 500mg of inositol hexanicotinate every time i eat something. don't take it on an empty stomach or it might cause intense flushing.