While ascending the stream, the lassitude produced by the climate was so great that Martyn's spirits sank under it: he thought he should "lead an idle, worthless life to no purpose.

Exertion seemed like death; indeed, absolutely impossible." Yet at the least he could write, "Even if I should never see a native converted, God may design, by my patience and continuance, to encourage future missionaries." This feeling of exhaustion was the prelude to a severe attack of fever, which assailed him almost immediately after his arrival; but happily not till he was safely lodged at Aldeen, in the kindly house of the Rev.
David Brown, where he was nursed till his recovery.

His friends wanted to keep him among the English at Calcutta, but his heart was set on ministering to the heathen, and the sights and sounds of idolatry that constantly met him increased his eagerness.

He once rushed out at the sight of the flames of a Suttee, hoping to rescue the victim, but she had perished before he reached the spot.
His arrival was when the alarm about the meeting at Vellore was at its height, and when the colony at Serampore had been forbidden to preach or distribute tracts in Calcutta.

He by no means agreed with all the Baptist doctrines, but he held in great esteem and reverence such men as Carey and Marshman, was glad to profit by their experience and instructions, and heartily sympathised in all their difficulties.