This is a very, very broad question. There is a ton of variance based on location (US, Europe, etc.), industry (agriculture, manufacturing, household, etc.), birth/race/gender (a male in the US South would have tremendous variance for example) and year (the 19th century saw a lot of innovation). It isn't a terrible question by any means it lacks the sort of precision needed to give a satisfying answer.

I am going to attempt a bit of an example to show how precision makes a difference on the answer here. First I am going to narrow it down in some particular ways to fit what I know. I am going to constrain my answers to a particular industry (agriculture) but I am going to narrow it down even further by eliminating large segments of agriculture to focus on the single family operated subsistence/cash crop farm. I am going to further narrow it down a bit artificially by putting the farm near the frontiers of the US and by giving the family a bit of status in the sense that they are white, western European immigrants of modest means. This would allow them to "stake a claim" on a farm and have a chance to establish a business/living. So I've now constrained the question to look something more like: What were the working conditions on a family farm in the US frontier in the 19th Century?

Believe it or not there are still some serious variances in the experiences that can be contained within this question as the frontier was very different in 1801 than it was in 1899 as was the technology. I will attempt to further constrain this down by making this more of a narrative about the westward migration and how it might have looked for a family in the 19th century. This story is purely fictional and attempts to give some insight into the what it might have been like to work down on the farm.

The "story" beings in 1805 with a young family fleeing the political turmoil in France. The husband, wife, and young sons worked for a fair sized farm and had managed to save enough to travel to western New York where they have just enough means to buy/barter a small cabin and plot of land from a distant relative who had the cabin as a fur trapper.

Work to establish the farm is difficult work. The husband spends much of his time clearing a few fields out of the flat land by cutting down trees and using a team of oxen to drag the trees out to the edge of the property where they are picked up and paid for by some employees of the local sawmill. The wife spends her time tending to a large garden and some chickens that help feed the family as well as spending time looking after the children (with more likely on the way). Days are mostly made up of physical labor in clearing the land and growing food enough to get by without the need of dipping into the money earned/saved by selling the raw timber. Some of the timber returns as lumber to which the family uses to build additional buildings. With the land clear they likely would have fashioned some basic farm equipment from the raw wood or perhaps purchased a newer cast iron plow bottom with which they would till and prepare the soil for planting grain. Once the crops were planted time could be devoted to either clearing more cropland or building/repairing sheds or barns to house a growing animal herd. Children could be expected to help with the animals at a young age and as they grew older they would be expected to lend a hand in the fields or with domestic tasks (cooking, cleaning, tending the garden, watching younger children, etc.) based on gender.

Let's move on to the next generation who are the children/grandchildren of the original family. They've been working on the farm since they were old enough to know how. The area is fairly well established with farms and there is opportunity to move west with horses and a wagon along with seeds and other supplies provided by the families as the new young family sets out for northern Indiana in the 1840s. Horses and oxen are a bit more plentiful as are the options for equipment and wagons that they pull. This combined with the flatter terrain make it somewhat easier for the family to clear their fields and establish their farm. Like their ancestors the family's children are expected to contribute to the farm work, but there is now time and means to visit the schoolhouse up the road and the children are able to read and write better than their parents. There is still a lot of hard labor in working with the animals on a near daily basis, but some of the inventions/tools available are making that labor easier/more efficient. Better harnesses and newer designs on implements makes it easier to get a team out into the field and allows more efficient work getting done before the animals tire.

Domestically better cooking utensils and stoves are available every year due to more industrialized processes in manufacturing the tools.

By the early 1870's a new generation is ready to head out west before the frontier closes. They take up what they have saved and board a train and head out to the plains where they are able to stake a claim near a creek in central Kansas. Instead of needing to ship/haul/bring supplies from the old farm they were able to purchase much of what they needed from the train depot. Kansas offered some challenges, there were fewer trees to clear, but the sod was best worked with some particular plows that were metal framed, and heavy bottomed that would turn the thick turf. This generation would begin to see more fruits from the industrial revolution as more and better farm implements were being shipped out via train. Steam tractors were showing up and while most families could not afford them to work the land, they often could rent time/usage for particular tasks (pulling stumps, cutting lumber, threshing grain). The ability to ship animals East for slaughter meant that domestic herds could be expanded for more than just subsistence (milk, eggs, meat). Indeed the expanded markets that the railroad brought to the farms mean that cash crops were more attractive and implements and domestic goods were more readily available.

I've sort of glossed over a lot of gritty sorts of details of the actual labor on the farms. The nature of the work would change on a seasonal basis (planting, harvesting, expanding, winter, etc.). Most of the "down time" would be spent in repairs or expansion of the operation.

I am sure there are other contributors to ask Historians that could tell you very interesting details and much better stories from their areas of expertise if the question is constrained enough to fit said areas. There are likely hundreds of books that could be written on just small areas on this sort of question if you can help narrow it down and I am sure you will get much better answers.