Before answering I have to apologize for my poor English skills, feel free to ask me something you didn't understand.

In short, as it often happens with Russian peasentry during times of turmoil: it was terrible and beyond being hopeless. Constant warfare, no food to be found anywhere, foreign troops plundering your lands, government and rebel forces trying either to enlist you or to rob you of your possessions, roads around villages occupied by bandits, imminent danger of Tatar slave raid leading to your adventurous, but sadly short life as a slave rower on an Ottoman war galley.

In not so short, reasons for completely abysmal death rates and unimaginable life conditions of Russian commonfolk found in this period are very complex and deeply rooted in previous decades as well as near collapse of Russian state system which lead to complete lack of control from ANY power pretending to own war-torn lands, further worsening the situation.

First signs of future problems to come happened long before Time of Troubles (or Smutnoe Vremya) and were, to a large extent, connected with extremely controversial reign of Ivan IV The Terrible. Largely unsuccessfull Livonian War (or, to be more precise, it's latter part, sometimes also called War of the Livonian Succession in Russian academic circles) led to enemy troops invading Russian border lands, burning and looting many towns and making peasantry run for their lives. War requisitions became extremely heavy burden as mounting resistance from alliance of Russian enemies demanded more and more resources in order to stabilize the situation. To add insult to injury, free-roaming Oprichnina emmisaries often enjoyed large degree of freedom when it came to them taking and exploiting people's possessions, a right they often vigorously practiced. Even moreover, there was also big plague outbreak around 1570, hunger became commonplace, many formerly lavish farmlands became desolated due either to constant warfare or because of unhealthy economical situation. This precursor to one of the bloodiest pages in Russian history came to be known as Porukha ("A disaster").

Political instability which came with the death of Ivan IV didn't help. He most certainly wasn't the best ruler Russia had ever seen, yes, and he also was a tyrant, but whatever talents he possessed his sons definetely lacked. His last male heir, king/tsar Fedor I The Blessed, wasn't an able ruler, and Russian de-facto leader during 1580-1590s came in the form of Boris Godunov, brother of Fedor's wife. Godunov decided to take desperate measures in order to fix crumbling Russian economy by imposing even more constraints on ordinary peasants: for example, he effectively enabled Russian landlords to officially manhunt runaway serfs for a period of up to five years before considering them to be lost forever.

Disastrous famine of 1601-1603 (also known as The Great Hunger, an event most likely caused by sudden and drastic climate change due to the eruption of Huaynaputina volcano which led to 10-week long stormy rains in summer and early snows in autumn destroying any crops on most parts of the Russian territory) led to even deeper crisis in peasants' lives. Whatever farmlands have been restored quickly became abandoned once again due to awful weather, insufficient amount of working hands and degrading administration system. People started to flee central regions, hoping to find better lives in the north (due to sea trade possibilities), near Don free estates or even trying to move as far as Syberia. Great swathes of starving peasants were slowly turning into raving mob gangs who tried to take food and shelter from other helpless people by force. Cannibalism became a common occurrence. Roads around the largest of towns and the smallest of villages became extremely dangerous due to uncountable amount of bandit groups ambushing, killing and looting everyone they could find.

The Time of Troubles became the last strike of an executioner's axe upon the poor head of Russian commonfolk. It was somewhat possible to at least somewhat unburden hungry masses when there was still functioning core administration but there was nothing of sorts to be found when hell broke loose and Russian Tsardom quickly defragmented into many disputed, ravaged regions with no central power to hold them together. Royalists didn't have neither unity nor sufficient forces to establish control upon dying en-masse populace, and Polish and Swedish armies definitely never considered serfs' problem as something worth looking at. Peasants who tried to participate in Bolotnikov's Rebellion of 1605 quickly started turning on their less optimistic brethren, robbing and slaying them no different to any other robbers and murderers. Those who tried to resist them perished in armed struggles, those who tried to support them were britally punished when the rebellion had been put down.

Due to the collapse of border defence system, Tatar outriders as well as renegade Cossacks were virtually unopposed and quickly realised how easy it was for them to grab something valuable fron beneath the collapsing Russian throne while no one's looking. In summer, entire villages were often taken away by nomad warbands as slave prizes in order to be sold somewhere in Crimea. Southern principalities turned into a deathtrap with population numbers plummeting into the ground. Thus, there were no more workers to farm the fields or repair damages inflicted by conflict, and people who relied on them soon also became an easy prey for many types of predators. In winter, small scraps of food villagers managed to somehow retain would've often been expropriated by passing Polish-Lithuanian troops as spoils of war. With their last supplies gone, wild animals trying to leave warzone ASAP and surroundings burnt to the ground, peasants' chances of living through winter were extremely grim and it was not uncommon for weary travellers to find entire neighbourhoods covered with bones of people left unburied as there wasn't a single living soul across many miles in any direction to do something about it.

It was essentially "damned if you do, damned if you don't" position with countrymen desperately clinging to every saving possibility only to be punished by circumstances again and again. Peasants from areas whose landlords decided to pledge their loyalty to Polish-supported False Dmitry quickly found out that their troubles have actually doubled since henchmen of The Thief From Tushino (one of the insulting nicknames given to False Dmitry II by populace) didn't feel like fulfilling their part of the deal (or, most likely, False Dmitry didn't have any real influence on them) and kept doing whatever they pleased. These "rogue" peasants also came under frequent attacks by Royalist forces who considered people simply doing their best to save their families and themselves to be traitors unworthy of mercy. After Sweden changed sides and declared war on Russia in 1610, another uncaring predator stepped on the scene, exploiting rural plowmen as every other force. It is worth noting that brutality towards local populace wasn't something out of the ordinary for an army from XVII century; in fact, it was quite common for any side of the war, but the sheer scale of destruction made The Time of Troubles to stand out even among other turbulent events in overall very bloody history of Russia.