All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There are some acts that are confirmed in the Sunnah which make the one who performs them deserving of the reward of a martyr, among which is to have a sincere intention for martyrdom. The one who has a sincere intention will get the reward of the martyr even if he dies on his bed.
Sahl Ibn Haneef narrated that the Prophet said: "Whoever sincerely asks Allah for martyrdom, Allah will grant him the ranks of the martyrs even if he died on his bed." [Muslim]
Another act is to be patient when there is plague. The Prophet said: "The one who flees from plague is like the one who flees from the battlefield (against the disbelievers), and the one who is patient with it, will get the reward of a martyr." [Ahmad with a chain of narration classified by Al-Arna’oot as sound]
It was also reported that the one who enjoins good and forbids evil gets the reward of a martyr. The Prophet mentioned a number of people who get the reward of a martyr, as reported by Ibn ‘Assaakir on the authority of ‘Ali and Al-Albaani classified it as authentic.
The wording of the Hadeeth is as follows: "The drowned person is a martyr; the person who is burned (to death) is a martyr, (the person who dies while he is away from his homeland is a martyr; the person who is bitten by a snake or scorpion is a martyr); the person who dies because of an abdominal ailment is a martyr; the person who dies beneath a collapsed structure is a martyr; (the one who falls from the top of a building and breaks his leg or neck and dies is a martyr; the one on whom a rock falls and he dies is a martyr; the wife who is jealous of her husband and suppresses her jealousy for the sake of Allah gets the reward of a martyr); the one who is killed while defending his wealth is a martyr; the one who dies while defending himself is a martyr; (the one who is killed while defending his Muslim brother is a martyr; the one who is killed while defending his neighbor is a martyr; and the one who enjoins good and forbids evil is a martyr)."
These are some Ahadeeth about the kinds of people who may get the reward of a martyr.
Allah knows best.