I often find myself in the following situation: a friend from work asks to borrow an object, such as a book or my bike or a piece of jewelry they might have seen me wear or money, to pay for food if we are eating out, for instance. I intensely dislike lending my possessions to others. Until recently, however, I always agreed to lend these things, and it would turn out they would forget to return to it, or return it much later than promised, or forget to give me a heads-up that they would return it later than promised, etc. It would make me very uncomfortable to ask them for that object back: I also observed that after such an interaction, that friend wouldn't initiate any conversations with me anymore.
I will admit that despite detesting lending my stuff, I did/do it because I want to be liked by others. I am looking for suggestions on how to handle the situation the next time someone asks for something, where my goal is to balance 1) being liked 2) saying no 3) not having to lie about why I don't want to lend something.
More context: I am in my early thirties and in grad school, and most of my friends are in their early twenties, having come here straight from undergrad. I also want to add that there are some things I am extremely generous for: I will happily share food I make, bring baked goods for friends, spend several hours helping people out with parts of their research that I am more of an expert on than them, sit in on their practice talks, listen to and give advice on any "life" issues they might ask advice for, etc. It's just things like my textbooks, bike, money, and clothes -- in other words, my material possessions -- that I strongly dislike lending.
We are all based in the USA, in northern California, if it matters.