relativistically speaking, you can get close to light speed, but matter can never travel
at light speed. Important distinction.
In terms of the thrust necessary to propel an object with an acceleration of

is quite high. Assuming you're already in space, for a spacecraft with a payload of, say 10000kg, about 11 tons, very light for any kind of manned spacecraft, you would have to apply a constant force of 98,000N. Let's say we want to speed this payload up to 10% light speed, seems like a small number, but bear with me. For this, we won't consider relativity at all, and will treat this under Newtonian gravity alone. So, at

it would take 3059107 seconds, or 35.4 days, to achieve .1c. That means that the spaceship will travel 9358135637449m before reaching that speed. That's 917,097,292,470,002 Joules of energy. It would take 3206633889.755252 moles of hydrogen combusting to produce that much energy. The weight of propellant necessary, in hydrogen alone, is 3206633kg. This also doesn't take into account that a large amount of the fuel would have to also be included in the payload section, since unburnt fuel is also being accelerated long with the payload.
Sorry for bursting the monkey poo bubble
