Once you reach about level 20, and have a healing spell, you should be able to utilize this method. Approach a giant (without a companion) and try to coax him away from any other giants or mammoths that might be near him. Do this by approaching him until he raises his club, and then slowly take a few steps backwards until you have him isolated from the rest of his friends. Use your shield to block his blows and heal yourself as necessary. Do not strike him back, just protect yourself. You may have to run away occasionally, to regenerate stamina and then immediately return and allow him to pummel you. Once you have the perk to heal health AND stamina, this process will go quickly. Your block level with rise quickly, as well as your overall level. (Restoration will also rise, although slowly.) Once you reach 100 block, make the ability legendary, and repeat the process. You will rise in levels very quickly, as well as obtain a lot of perks, that you can apply anywhere you want!