What does one mean by suffering? If you are speaking of sickness, aches and pains, there is little choice in the matter.
If you are speaking to societal suffering, and people living in poverty, being unhappy in their relationships, feeling unwanted or underappreciated, then a lot of choice exists.
It is understanding this, like the old adage - serenity to accept the things I cannot change, the strength to change the things that I can, and the wisdom to know the difference.
No one chooses to be in pain, to starve, or to be abused. Nobody asks for this to happen and then complains about it. Logically speaking, it would be comparable with juxtapositions. When two statements are directly contradictory and placed next to each other. Nobody says "I chose to be in an abusive relationship and it's so awful and terrible.". Masochism is suffering by choice.
While you can choose to suffer (e.G. Always being on the down and chosen pessimism) there are many instances in which suffering is forced upon you, for example minorities suffer due to an imperfect view towards racial relations, such as mistakes that can happen in the criminal justice system. Life is inherently different from person to person, based on both how a subject seems themselves or how the world sees a subject. Poverty is perhaps the most common form of suffering. Living in poverty hinders your ability to get a job to help yourself out. In poverty, you might live in a bad neighborhood, not own a car or phone or professional clothes. Often times public transport does not reach these areas. Higher education is unavailable due to steep tuition and the fact that many people drop out in high school in order to help their family pay the bills. Suffering can be a choice, but when its not, its a continuing circle that only brings more pain.
There are many forms of pain, and not all can be helped. For example, physical/mental disabilities brought upon by genetic disorders cannot be helped, but if you are referring to other kinds of suffering, like anxiety or depression, then it is possible to take steps to amend those issues. I'm still not sure if undergoing them is a choice however...