I have gone through your post in which you have asked about any power booster capsules or tablets available in the market which could be taken before hitting to Gym so as to curb the weakness.
In fact, there are many such products available which claim to provide energy & help in muscle building (due to ethical reasons, I can't mention their names in this forum).
is a multivitamin
But these products are only dietary supplements & should not compromise on routine healthy food such as:
1. Consume more of natural diet like fresh fruits, green vegetables, milk, eggs, wheat, etc.
2. Avoid oily and junk food.
3. Stay away from smoking
4. Best is to stay active, exercise regularly, avoid stress
, get good sleep, think positive and stay happy.
Wish you a healthy life.