I HAVE seen my future and it is full of beans, both literally and metaphorically. As well as upping my bean count, there will be a lot of vegetables, no meat, long periods of hunger and hardly any alcohol. But in return for this __________ discipline, my future will also be significantly longer and sprightlier. I am 52 and, on my current diet, can expect to live another 29 years. But if I change now, I could gain an extra decade and live in good health into my 90s.

Fill the gap with an adjective that reflects the context of the previous sentence