Stimulation, increased energy, elevated mood and self-confidence, a nice toasty feeling afterwards, quicker cooling after exercise, optimum alertness achieved faster in the day if done early.
Definitely lots of psychological benefits.
I do combine it with meditation and exercise. All three seem to have mutually-reinforcing effects.
I've found the best habits reinforce each other. Diet, exercise, better sleep.. they all interact and make each other stronger.
I have also found that a brisk morning walk in the cold (deliberately wear just a hoodie and shorts in near freezing temps) has helped as well. Maybe it's the sunlight, maybe it's the exercise, maybe it's the cold but I feel like it gets my hormones into better shape and I have more energy (specifically referring to T, and for example I have had very mild acne, which I hadn't seen in about 15 years).
Definitely lots of psychological benefits.
I do combine it with meditation and exercise. All three seem to have mutually-reinforcing effects.