The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence. 

The ability and willingness of older workers to continue working depend also on their personal state of health, conditions of work and motivation. Older workers face special difficulties at work, such as greater vulnerability to strain in a working environment, problems in adapting to new working methods and techniques and stresses associated with the transition to retirement. Ensuring appropriate conditions of work for older persons is crucial.
Older workers' need of （） to solve difficulties.