Combining ideas and sentences using linkers.	

In the past most people’s work involved physical labour.
They got plenty of exercise every day.

Nowadays people have a wide choice of food.
Not all of this food is healthy.

People have busy lives.
It is often difficult to find time to do exercise.

In the past food was expensive.
Nowadays it is relatively cheap.

Food produced by factory farming methods is often cheaper for the consumer.
Many believe the use of chemical fertilizers and pesticides make this kind of food less healthy. 

Many people find it difficult to find the time to do regular exercise.
High levels of air pollution often deters people from taking exercise outdoors.

Indoor gyms offer a convenient way of getting exercise for city dwellers.
Not everyone lives or works near to a gym.
They are often expensive.

People work long hours.
They do not always have time to prepare or select the healthiest kinds of food.

Possible answers 	

In the past most people’s work involved physical labour.
For this reason, / Therefore, / Consequently, / As a result, they got plenty of exercise every day.

Nowadays people have a wide choice of food.
However, Not all of this food is healthy.

People have busy lives.
For this reason, / Therefore, / Consequently, / As a result,   it is often difficult to find time to do exercise.

In the past food was expensive whereas nowadays it is relatively cheap. 

Food produced by factory farming methods is often cheaper for the consumer.
However, many believe the use of chemical fertilizers and pesticides make this kind of food less healthy. 

Many people find it difficult to find the time to do regular exercise.
What is more, / Furthermore, / Moreover, high levels of air pollution often deters people from taking exercise outdoors.

Indoor gyms offer a convenient way of getting exercise for city dwellers.
However, not everyone lives or works near to a gym.
Besides, they are often expensive.

People work long hours.
For this reason, / Therefore, / Consequently, / As a result,  they do not always have time to prepare or select the healthiest kinds of food.
OR 
Due to long working house, people do not always have time to prepare or select the healthiest kinds of food.