have too much on one's plate

have (got) a lot / enough / plenty /too much on one's plate (have a lot of things to do or too much to cope/deal with ) — иметь массу дел; иметь уйму дел; дел по горло; дел выше головы; дел выше крыше; дел невпроворот; ~ забот полон рот; столько всего навалилось

Example 1: I don't want to get involved. I've got enough on my plate as it is, I don't need any more trouble.

Example 2: There are an awful lot of things on my plate right now, I could not take on any other obligation.

Example 3: She did not want to bother Brian with her requests, because he had so much else on his plate.

Example 4: Give it up before it is too late. Try and find yourself a nice, decent husband and settle down. It is not good for a physician to confide personal details of his life to a patient. I reciprocate your seasonal greetings. Now I fear we really must stop corresponding. I just have too much on my plate. (Lying together. Thomas, D M.)

Example 5: It is a very long time since I heard from you. I wondered how you are getting on? Given your unusual tastes, one naturally worries. Of course, I told you I had too much on my plate to be able to continue our correspondence, and I hope this is the reason you stopped writing. On the other hand, similar statements of mine have never prevented you from writing back in the past. I say that in all affection. l would like to hear from you. (Lying together. Thomas, D M.)

This expression transfers a loaded or overloaded dinner plate to other activities. (Answers.com)

see also
[have one's work cut out]
[tough row to hoe]