Re: Being an Uke/Nage
when you are being blocked, it means that you havn't found the path of least resistance yet nor the moves that will fully control your partner without hurting him.
if you are blocked, stop the technique. do not ever force a technique even if at the end you are successful at throwing your uke. this is mediocre practice and will set you up for bad habits when you get promoted to a more senior level.
try to find out where your uke cannot resist but if that doesn't work, ask your sensei to come over and help.
there needs to be some level of cooperation between nage and uke so they can learn together. aikido is not a contest of strength nor who can throw/resist best. Resistance is perfectly ok but both nage and uke need to suit resistance according to their partners level so that both can learn. This is the unspoken rule which a lot of people do not know and where some people are not sensitive to. As both partners knowledge increases, then resistance/intensity can also increase.
Uke offers resistance to nage so that nage can understand his technique better and understand ukes reaction to what he's doing. You do not offer resistance to nage to test him.
As Endo sensei said, do not think of small goals like throwing uke hard rather practice so that you can understand how yo use your body correctly and its state.
Also I've changed my understanding of aikido these past decades. Aikido is not about nage and the techniques per se but aikido is about uke.