Stolidly

I sat stolidly puffing at my pipe and skipping over the pages of Henri Murger's Vie de Bohème.

Source: tatoeba (6309920)

On once more we swung, bumping uneasily along in the antique narrow-gauge coach, with gloomy woods and gathering night outside, shouts and songs (and quacks) inside—this was not at all the sort of train ordained by the logical strategists in Paris—then grinding to a stop at a mysterious halt which was no more than a nameboard in the pinewoods, without even a footpath leading to it, but nevertheless with a solitary passenger stolidly waiting.

Source: wiktionary