“I have a car”, “I have confidence”, “I have a chronic knee pain” and etc., these simple and ubiquitous phrases in English are not so straightforward in Japanese.

持っている (持つ＋接続助詞て＋補助動詞いる) is a common, and straightforward-for-English-speakers expression.

• 私は車と原付きを持っている -> I have a car and a moped
• 彼は沢山お金を持っている -> He has a lot of money

Note that “I have such and such” is always 持っている, which is the continuous/progressive tense. However, “to have such and such” will be in the simple present tense as 持つ.

• 家を持つのが私の夢だ -> My dream is to have, own, a house
• 自分に自信を持つ事が必要だ -> It is important to have confidence in yourself

When it comes to animate things, 持っている is not used, and instead いる (=there is/are) is used.

• 私は子供が二人います -> I have two children
• うちには猫が二匹います -> There are two cats in my place. I have two cats
  • Note that when it comes to pets, うちには～がいる is used, instead of 私は～がいる is used. The alternative is 私は猫を二匹飼っている -> I keep two cats as pets

For most other inanimate, abstract things, ある (there is/are) is often used. In many cases you can use both 持っている and ある.

• 私は自信を持っている -> I have confidence
• 私には自信が有る -> There are confidence in me. I have confidence

• 彼女は沢山の経験を持っている -> She has a lot of experiences
• 彼女には沢山の経験が有る -> There are a lot of experiences in her. She has a lot of experiences

• 私は自分の考えを持っている -> I have my own opinion
• 私には私の考えが有る -> There is my own opinion in me. I have my own opinion

However there are many things that you can say “I have such and such” in English, but you cannot use 持っている.

• I’ve got a bad feeling about this
  • 私はこれには嫌な感じを持っている
  • 私はこれには嫌な感じがする -> I feel bad about this

There are no definitive rules for these, and you just have to learn as they are.

Also refer to this article on the difference between ある and いる.

For something undesirable, 抱える is often used as well.

• 彼は慢性の腰痛を抱えている -> He has a chronic back pain