It won't be a miracle but you should look into supplements E.g Amino Acids/Herbs/Vitamins/Minerals, some of which are quite effective, like:
*DLPA = A 50/50 ratio of Dextro- and Levo-Phenylalanine (D-PA is one of the few amino acids that can be utilized in its dextro isomer form)
-The LPA is a precursor to Tyrosine, which is a precursor to Neurotransmitters, and increases the plasma Neurotransmitter levels, like Dopamine ('Feel Good' Neurotransmitter) and Norepinephrine (= noradrenaline, works alongside epinephrine (= adrenaline) to give the body sudden energy in times of stress).
-The DPA is the bit that will help the most though. I don't know enough about how it works yet so I'll just paraphrase what's written on the back of the bottle I have at home.. "DPA inhibits the action of enzymes that break down Endorphins and Enkaphalins (the cosy endogenous pain-killing proteins that bind to opioid receptor sites in the brain). By inhibiting these enzymes, DPA may extend the life of Endorphins and Enkaphalins and their positive influence on comfort levels"
So basically after taking around 1000-2000mg on an empty stomach for a few weeks (not sure if it works straight away) you'll have more endorphins/enkaphalins floating around, and when opiates are ingested and more endorphins/enkaphalins are released, they will hang around for longer. Basically potentiates a bit and boosts duration apparently a great deal. I have just ran out after taking for around 4 weeks and am awaiting a new bottle in the mail, the good thing is once you've taken it for a while it doesn't stop working the moment you run out, e.g. people say they notice the potentiation for around a month after stopping.
*Nigella Sativa oil/seeds = The oil works the best just for convenience and potency, but apparently the seeds are like 50% oil by weight anyway. If you order a good brand off internet auction sites, you will definately notice an increase in effect of your opiate of choice after having a swig of this oil.. most people recommend starting with 1-2tsp at first, some say it worked so well they nodded out/puked etc off their normal dose.. again they could be the lucky few, but I find Nigella Sativa oil (from a quality source) really does potentiate well, as there is genuine opioid agonists contained within (e.g. Thymaquinone, etc.)
*Enzyme Inducers like - {Cimetadine = 'Tagamet', Grapefruit Juice, Quinine etc.} - Too many threads about ol' favourites like these already so I won't elaborate.
*Sedating Antihistamines like Diphenhydramine, Promethazine, etc. can add a bit of warmth and sedation, I don't really use them myself.
*Bacopa Monnieri = 'Brahmi' - This stuff I have in a herbal combo capsule with:
-3000mg Bacopa Extract, and
-3000mg Gingko Biloba Extract.
I have noticed when I take a tablet of this in the morning, I can halve my oxycodone (legally prescribed) dosage for the morning and still need a coffee to stop me nodding off in class.. plus the gingko/brahmi mixture boosts my brain-power without a doubt, definately feel the benefit from this stuff, however subtle it may be.
-Gotu Kola would be a good adjunct to this mix.
* Many other herbs I don't have much experience with, yet have heard a few reports of increased effects, whether due to enzyme inhibition/induction or synergism.. such as
-Milk Thistle (I didn't notice a difference personally but my product wasn't the best quality by any standards..)
-Kava Kava (Good benzo alternative)
-Non-recreational-yet-sedating herbs like Valerian, Hops, Passionflower (beware mild MAOI properties), Chamomile, Lemon Balm, Skullcap, Californian Poppy, and many, many more
*NMDA Antagonists like
-DXM (= Dextro-Methorphan) - Lots of good info about this on Bluelight and other sites
-Ketamine, memantine etc.
-Magnesium is actually an NMDA Antagonist and is also just great for relieving mild anxiety/muscle cramps etc.
Most persons addicted to any drug (opiates, ciggerettes, coffee, meth, etc) is probably deficient in this vital mineral, always worth having a GOOD Magnesium supplement in the cupboard (Note- Don't buy a badly-absorbed form like Mag-Oxide or the like, go for a Chelated form or something like Mag Citrate, powders like "Muscle-Eze" normally have a bunch of other useful things like Glutamine, Vit B's, etc.
*Certain other Amino Acids can help, I don't know enough to elaborate though..
*If LEGAL in your Area - Cannabis always boosts people's analgesia and general body stone a GREAT DEAL
There's probably many more things I could write if it wasn't 2:08 in the morning here in Kiama.
This is just meant to be the tip of the iceberg, thought I'd help you out cos although I'm probably much younger than you and certainly don't have anywhere near as large a tolerance, I know how hard it is to keep tolerance from rising, etc.
Peace man, if you have any questions just ask, there should be someone on this great useful site that knows the answer.